Oil Change Time
Race Director
Joined: Aug 2000
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BTW, I thought I read something about a new motor oil with a viscosity index of 0W10 -
Last edited by Joe C; Jul 8, 2017 at 05:37 AM.
Safety Car
Joined: Jun 2006
Posts: 4,008
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From: Ashland, OH
When I went to change the oil for the first time in my new 1985 in July, 1985 I read the owners manual for its recommendations. It says to use 10W30 oil. In bold type, it says "DO NOT USE 10w-40 VISCOSITY OIL IN YOUR CORVETTE". At the time (1985) 10W-40 was a very popular and readily available mult-grade motor oil. 10W-30 was a new grade, and not widely stocked. I had to special-order 10W-30 for my car for about a year, when after that it was generally available in-stock. I have never un-covered an explanation for the "do not use 10-40" that is in the 85's Owner Manual.
I run straight grade 30W in all my engines. I use Delo 400 for the additive package. I live in SoCal, so I don't encounter much low-ambient start-up temperature. I used GTX 10-30 for the first 10 years, then it sat in storage for 12 years, never started. In about 2006 I began to run it again, and I probably went to the Delo 30W at that time. For the most recent change earlier this year, I went back to the GTX 10-30. The way I use this car has changed. My thinking is that it is now going to get a LOT of starts without it ever really getting up to temp, so the lower viscosity as start-up will be of benefit.
So I use oil(s) that I've had good experience with, and that meet the OEM spec for the engine / model year / usage / temperature they are going into. Simple as that.
This zinc thing has been blown all out of proportion. I've spent a lot of time educating myself on the subject, and am comfortable with my choices and strategies. Different people will have different conclusions and strategies, but if the oil and viscosity they choose meets the criteria their research says they should use, they will be comfortable with their decisions and choices too.
Knowledge is power.
I run straight grade 30W in all my engines. I use Delo 400 for the additive package. I live in SoCal, so I don't encounter much low-ambient start-up temperature. I used GTX 10-30 for the first 10 years, then it sat in storage for 12 years, never started. In about 2006 I began to run it again, and I probably went to the Delo 30W at that time. For the most recent change earlier this year, I went back to the GTX 10-30. The way I use this car has changed. My thinking is that it is now going to get a LOT of starts without it ever really getting up to temp, so the lower viscosity as start-up will be of benefit.
So I use oil(s) that I've had good experience with, and that meet the OEM spec for the engine / model year / usage / temperature they are going into. Simple as that.
This zinc thing has been blown all out of proportion. I've spent a lot of time educating myself on the subject, and am comfortable with my choices and strategies. Different people will have different conclusions and strategies, but if the oil and viscosity they choose meets the criteria their research says they should use, they will be comfortable with their decisions and choices too.
Knowledge is power.
Was reading up on that Delo straight 30w. Looks like good stuff honestly!
Now with a 30 year old plus SBC with 80-180k miles I'm willing to bet you any amount of money you can run 20w50 in these old pigs just fine lol!
Last edited by Cjunkie; Jul 8, 2017 at 06:07 PM.
Thread Starter
Le Mans Master
Joined: Dec 2005
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From: Communist Colorado
When I went to change the oil for the first time in my new 1985 in July, 1985 I read the owners manual for its recommendations. It says to use 10W30 oil. In bold type, it says "DO NOT USE 10w-40 VISCOSITY OIL IN YOUR CORVETTE". At the time (1985) 10W-40 was a very popular and readily available mult-grade motor oil. 10W-30 was a new grade, and not widely stocked. I had to special-order 10W-30 for my car for about a year, when after that it was generally available in-stock. I have never un-covered an explanation for the "do not use 10-40" that is in the 85's Owner Manual.
I run straight grade 30W in all my engines. I use Delo 400 for the additive package. I live in SoCal, so I don't encounter much low-ambient start-up temperature. I used GTX 10-30 for the first 10 years, then it sat in storage for 12 years, never started. In about 2006 I began to run it again, and I probably went to the Delo 30W at that time. For the most recent change earlier this year, I went back to the GTX 10-30. The way I use this car has changed. My thinking is that it is now going to get a LOT of starts without it ever really getting up to temp, so the lower viscosity as start-up will be of benefit.
So I use oil(s) that I've had good experience with, and that meet the OEM spec for the engine / model year / usage / temperature they are going into. Simple as that.
This zinc thing has been blown all out of proportion. I've spent a lot of time educating myself on the subject, and am comfortable with my choices and strategies. Different people will have different conclusions and strategies, but if the oil and viscosity they choose meets the criteria their research says they should use, they will be comfortable with their decisions and choices too.
Knowledge is power.
I run straight grade 30W in all my engines. I use Delo 400 for the additive package. I live in SoCal, so I don't encounter much low-ambient start-up temperature. I used GTX 10-30 for the first 10 years, then it sat in storage for 12 years, never started. In about 2006 I began to run it again, and I probably went to the Delo 30W at that time. For the most recent change earlier this year, I went back to the GTX 10-30. The way I use this car has changed. My thinking is that it is now going to get a LOT of starts without it ever really getting up to temp, so the lower viscosity as start-up will be of benefit.
So I use oil(s) that I've had good experience with, and that meet the OEM spec for the engine / model year / usage / temperature they are going into. Simple as that.
This zinc thing has been blown all out of proportion. I've spent a lot of time educating myself on the subject, and am comfortable with my choices and strategies. Different people will have different conclusions and strategies, but if the oil and viscosity they choose meets the criteria their research says they should use, they will be comfortable with their decisions and choices too.
Knowledge is power.
So in a years difference, it went from 10W30 to 5W30.... interesting... I guess the 5W30 was the new thing back then....
Le Mans Master
Joined: Jul 2004
Posts: 6,227
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From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
When I went to change the oil for the first time in my new 1985 in July, 1985 I read the owners manual for its recommendations. It says to use 10W30 oil. In bold type, it says "DO NOT USE 10w-40 VISCOSITY OIL IN YOUR CORVETTE". At the time (1985) 10W-40 was a very popular and readily available mult-grade motor oil. 10W-30 was a new grade, and not widely stocked. I had to special-order 10W-30 for my car for about a year, when after that it was generally available in-stock. I have never un-covered an explanation for the "do not use 10-40" that is in the 85's Owner Manual.
I run straight grade 30W in all my engines. I use Delo 400 for the additive package. I live in SoCal, so I don't encounter much low-ambient start-up temperature. I used GTX 10-30 for the first 10 years, then it sat in storage for 12 years, never started. In about 2006 I began to run it again, and I probably went to the Delo 30W at that time. For the most recent change earlier this year, I went back to the GTX 10-30. The way I use this car has changed. My thinking is that it is now going to get a LOT of starts without it ever really getting up to temp, so the lower viscosity as start-up will be of benefit.
So I use oil(s) that I've had good experience with, and that meet the OEM spec for the engine / model year / usage / temperature they are going into. Simple as that.
This zinc thing has been blown all out of proportion. I've spent a lot of time educating myself on the subject, and am comfortable with my choices and strategies. Different people will have different conclusions and strategies, but if the oil and viscosity they choose meets the criteria their research says they should use, they will be comfortable with their decisions and choices too.
Knowledge is power.
I run straight grade 30W in all my engines. I use Delo 400 for the additive package. I live in SoCal, so I don't encounter much low-ambient start-up temperature. I used GTX 10-30 for the first 10 years, then it sat in storage for 12 years, never started. In about 2006 I began to run it again, and I probably went to the Delo 30W at that time. For the most recent change earlier this year, I went back to the GTX 10-30. The way I use this car has changed. My thinking is that it is now going to get a LOT of starts without it ever really getting up to temp, so the lower viscosity as start-up will be of benefit.
So I use oil(s) that I've had good experience with, and that meet the OEM spec for the engine / model year / usage / temperature they are going into. Simple as that.
This zinc thing has been blown all out of proportion. I've spent a lot of time educating myself on the subject, and am comfortable with my choices and strategies. Different people will have different conclusions and strategies, but if the oil and viscosity they choose meets the criteria their research says they should use, they will be comfortable with their decisions and choices too.
Knowledge is power.
Last edited by Cruisinfanatic; Jul 8, 2017 at 09:37 PM.
Team Owner
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From: Park City Utah
And I'm failing to see how Delo 30w is aligned w/the OEM specs.
Team Owner
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
You have a flat tappet cam that needs zinc phosphate.
Most synthetics do not have this additive to promote good CAT life.
I chose syn Mobil1 hi-mileage and added a pint of STP for the extra ZP boost.
My new cam ran over 40K on this without a hitch.
Just sayin,
Most synthetics do not have this additive to promote good CAT life.
I chose syn Mobil1 hi-mileage and added a pint of STP for the extra ZP boost.
My new cam ran over 40K on this without a hitch.
Just sayin,
Race Director
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here's my take on oil additives - the oil companies, in conjunction with the engine manufactures, carefully formulate the oil/additive blend of the motor oil. they spend a lot of time and money on this, so I don't have to give it much thought. when you add something, while it might be beneficial in one area, it will, most likely, upset the balance of the other additives, that is, change the percentages and dilute the formula. here's a cut and paste from pelicanparts/porsche911 forum on the STP additive -
The STP Oil Treatment is supposed to be added with each oil change. It comes in one formulation (black bottle, $4.32) for cars with up to 36,000 miles, another (blue bottle, $3.17) for cars that have more than 36,000 miles or are more than four years old. We used the first version for the first 36,000 miles, the second for the rest of the test ---- again, with Pennzoil 10W-30.
When we disassembled the engines and checked for wear and deposits, we found no discernible benefits from any of these products.
The bottom line: We see little reason why anyone using one of today's high-quality motor oils would need these engine/oil treatments. One notable effect of STP Oil Treatment was an increase in oil viscosity; it made our 10W-30 oil act more like a 15W-40, a grade not often recommended. In very cold weather, that might pose a risk of engine damage.
When we disassembled the engines and checked for wear and deposits, we found no discernible benefits from any of these products.
The bottom line: We see little reason why anyone using one of today's high-quality motor oils would need these engine/oil treatments. One notable effect of STP Oil Treatment was an increase in oil viscosity; it made our 10W-30 oil act more like a 15W-40, a grade not often recommended. In very cold weather, that might pose a risk of engine damage.
again, not trying to flame anyone, just expressing my opinion -
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Team Owner
Joined: Aug 2004
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From: Park City Utah
no flames my friend, and, to each his own. it's your car, so you can do pretty much what you want.
here's my take on oil additives - the oil companies, in conjunction with the engine manufactures, carefully formulate the oil/additive blend of the motor oil. they spend a lot of time and money on this, so I don't have to give it much thought. when you add something, while it might be beneficial in one area, it will, most likely, upset the balance of the other additives, that is, change the percentages and dilute the formula. here's a cut and paste from pelicanparts/porsche911 forum on the STP additive -
one question - why 3/4 bottle?
again, not trying to flame anyone, just expressing my opinion -
here's my take on oil additives - the oil companies, in conjunction with the engine manufactures, carefully formulate the oil/additive blend of the motor oil. they spend a lot of time and money on this, so I don't have to give it much thought. when you add something, while it might be beneficial in one area, it will, most likely, upset the balance of the other additives, that is, change the percentages and dilute the formula. here's a cut and paste from pelicanparts/porsche911 forum on the STP additive -
one question - why 3/4 bottle?
again, not trying to flame anyone, just expressing my opinion -
"Rejected Option 2: Adding zddp additives to 800 ppm oil to increase the level. I believe that zddp additives are questionable. As evidence of this, in publication SAE 860373 (again, no link), Figures 5 and 6 show that the ability of 800ppm zddp to provide protection is highly dependent on the detergent package used. Depending on the detergent formulation, 800ppm oil can pass the Rocker Arm Distress Rating test with scores of 0, 5.6, or 6.9 (Pass Limit = 10), or fail it with ratings of 29, 30.6, 44,4, or 62.5! That's right-- detergent makeup can allow the same 800ppm oil to either pass the test by 50%, or fail it by six times the limit! Big difference! So adding an additive might work to improve your oil, but it might make it worse-- possibly much worse. Unless you know the exact composition of the additive package in your starting oil and the exact chemical composition of the zddp additive you're adding, I believe you're just gambling by simply dumping in a zddp additive."
Who here is a chemist and can ascertain the exact chemical composition of their "go-to" oil? None of us. So why are we "playing" chemists and making our own lube potions? Seeking longer life? How long? How long is "long enough"?
Folks, we aren't lube engineers...and we're not chemists; the oil companies are and they produce the best products available. Why are we arbitrarily pouring potions into our cars' orifices?? I know why...but it ain't necessary. How long, is long enough? Engines today last so long that the car falls apart around the engine. How long should an engine last?
Last edited by Tom400CFI; Jul 9, 2017 at 12:58 AM.
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Supporting Vendor
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My 2 Cents !
SAE has determined and I agree with that most (maybe 80%) of engine wear occurs at start-up. Hence the quicker the oil gets there the better. I think that's why most new vehicles use a 0W-20 or 30 - especially a quality synthetic that stands up to the demands of the 20 or 30 part number.
That said most Vettes are garage queens - limited starts and perhaps more modified HP than most ? So I recommend for my customers 15 or 20W-50 Amsoil because under WOT their midget bearings need help ! (Oh midget bearings - think SBC vs. BBC )
If zinc is an issue Amsoil has an answer for that too ! greg
SAE has determined and I agree with that most (maybe 80%) of engine wear occurs at start-up. Hence the quicker the oil gets there the better. I think that's why most new vehicles use a 0W-20 or 30 - especially a quality synthetic that stands up to the demands of the 20 or 30 part number.
That said most Vettes are garage queens - limited starts and perhaps more modified HP than most ? So I recommend for my customers 15 or 20W-50 Amsoil because under WOT their midget bearings need help ! (Oh midget bearings - think SBC vs. BBC )
If zinc is an issue Amsoil has an answer for that too ! greg
Last edited by BlowerWorks; Jul 9, 2017 at 10:27 AM.
Thread Starter
Le Mans Master
Joined: Dec 2005
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From: Communist Colorado
^THIS^ ...which was also covered in the link that I provided. In fact, in that link it was explained how adding zinc additives can actually hurt the protective properties of the oil that you're adding it to. Here is the quote from that part of the write up:
"Rejected Option 2: Adding zddp additives to 800 ppm oil to increase the level. I believe that zddp additives are questionable. As evidence of this, in publication SAE 860373 (again, no link), Figures 5 and 6 show that the ability of 800ppm zddp to provide protection is highly dependent on the detergent package used. Depending on the detergent formulation, 800ppm oil can pass the Rocker Arm Distress Rating test with scores of 0, 5.6, or 6.9 (Pass Limit = 10), or fail it with ratings of 29, 30.6, 44,4, or 62.5! That's right-- detergent makeup can allow the same 800ppm oil to either pass the test by 50%, or fail it by six times the limit! Big difference! So adding an additive might work to improve your oil, but it might make it worse-- possibly much worse. Unless you know the exact composition of the additive package in your starting oil and the exact chemical composition of the zddp additive you're adding, I believe you're just gambling by simply dumping in a zddp additive."
Who here is a chemist and can ascertain the exact chemical composition of their "go-to" oil? None of us. So why are we "playing" chemists and making our own lube potions? Seeking longer life? How long? How long is "long enough"?
And ^THIS^ too.
Folks, we aren't lube engineers...and we're not chemists; the oil companies are and they produce the best products available. Why are we arbitrarily pouring potions into our cars' orifices?? I know why...but it ain't necessary. How long, is long enough? Engines today last so long that the car falls apart around the engine. How long should an engine last?
"Rejected Option 2: Adding zddp additives to 800 ppm oil to increase the level. I believe that zddp additives are questionable. As evidence of this, in publication SAE 860373 (again, no link), Figures 5 and 6 show that the ability of 800ppm zddp to provide protection is highly dependent on the detergent package used. Depending on the detergent formulation, 800ppm oil can pass the Rocker Arm Distress Rating test with scores of 0, 5.6, or 6.9 (Pass Limit = 10), or fail it with ratings of 29, 30.6, 44,4, or 62.5! That's right-- detergent makeup can allow the same 800ppm oil to either pass the test by 50%, or fail it by six times the limit! Big difference! So adding an additive might work to improve your oil, but it might make it worse-- possibly much worse. Unless you know the exact composition of the additive package in your starting oil and the exact chemical composition of the zddp additive you're adding, I believe you're just gambling by simply dumping in a zddp additive."
Who here is a chemist and can ascertain the exact chemical composition of their "go-to" oil? None of us. So why are we "playing" chemists and making our own lube potions? Seeking longer life? How long? How long is "long enough"?
And ^THIS^ too.
Folks, we aren't lube engineers...and we're not chemists; the oil companies are and they produce the best products available. Why are we arbitrarily pouring potions into our cars' orifices?? I know why...but it ain't necessary. How long, is long enough? Engines today last so long that the car falls apart around the engine. How long should an engine last?
Melting Slicks
Joined: Nov 2013
Posts: 3,451
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From: Greater Cincinnati Area.
I read a study/link attached to one of the oil threads from a year or so back, and they claimed that low zinc was very bad for older engines. That 800-11200 (I think? I've slept since then.) was good, but it worked on a curve and too much is as bad as not enough.
Their point being that there's a sweet spot and just dumping in zinc is a no-no. They basically concur with what is posted here.
Their point being that there's a sweet spot and just dumping in zinc is a no-no. They basically concur with what is posted here.
Last edited by confab; Jul 9, 2017 at 01:06 PM.
Race Director
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at some point, folks need to put your faith in the API, the oil companies, and car manufacturer's recommendations. i'm pretty sure these guys are a lot smarter than most everyone here. the current "SN' spec is backward compatible. it's going to work just fine, contrary to all the on-line hearsay, BS, and marketing hype. use a quality, name brand oil, follow the recommended weight or viscosities, and change it at the proper intervals, and you're good to go. do this, and there's no reason you can't cruise to 300K miles. then again, if you want to add something, well, that's pretty much your business. personally, oil is one less thing I have to worry about.
Last edited by Joe C; Jul 9, 2017 at 01:32 PM.
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
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need to edit my original post -
well, it had enough and still has enough right out of the container! just sayin' -
...and my original cam is running 160K without a hitch and without ADDITIONAL zinc. the first 150K was on 10W30 dino. just sayin' -
Last edited by Joe C; Jul 9, 2017 at 03:53 PM.