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If you search, you will find all kinds of information suggesting what oil, additives, etc, you should use. I had a '70 LT-1 with the factory engine and wanted to use the best available as well. Turns out that if you have a vintage base engine or a solid lifter high performance one, your mechanic made an excellent recommendation.
I fully understand the need for an oil with the higher levels of ZDDP, for engines with flat tappet camshafts. But unless you live in an area where the air temperatures remain relatively warm, 100% of the time, I would think that a 15W-40 oil is a little heavy. If it were my car, I'd be looking at a Brad Penn brand oil, if it's still made, in either a 5W or 10W-30 weight. FWIW, Amsoil also makes a synthetic oil, with the proper level of ZDDP, specifically for flat tappet applications.
I would use the correct oil, either synthetic or conventional, with at least 1200 PPM ZDDP. I would NOT use a diesel oil, no matter what you read, since why would you when a proper gas oil is available and most likely superior? I use Mobil 1/Castrol Edge in my ROLLER CAMMED L-82 355 0W-40, European Formula, but not a flat tappet cammed engine, any longer.
A 15W weight oil is perfectly fine for temps over 32 degrees.....78 C3 Owners manual....
Last edited by jb78L-82; Jun 19, 2020 at 10:06 AM.
15-40 Rotella was the hot ticket before they came out with all of these high zinc oils. If you're in a warmer climate, then you're OK. If not, then there;s VR1,Luxas, etc.
Just because Rotella is designed for diesels, it doesn't mean it's not to be used with gas powered vehicles. Diesels have a higher demand on wear and sludge control.
I've used it, also Valvoline, and Lucas with no issues. You can use race oil if you don't have a catalytic converter, because zinc will contaminate it, or so they say.
Valvoline VR-1 is good, if you want Mobil use 15-50. Syn pours thinner than dino oil
I think syn is a waste really for an old motor. People will argue about oil and secret sauces all day lol
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Maybe you need to read what I said: "........or any gasoline engine they have ever manufactured". Rotella or any diesel oil is just not necessary when gasoline oils with higher zinc are still readily available, dino or synthetic.
The Rotella Diesel oil nonsense has been around for quite a while, and I, as well as others, logically, suggest using a gasoline oil in gas engines and Diesel oil in Diesel engines, which that oil is made for....
Do GM engineer's recommend Rotella in ZR1's, Z06's or any gasoline engine they have ever manufactured? There's a reason why they don't.
Correcto Mundo^^^^^^^^^^^^^^
GM has NEVER recommended a Diesel oil for ANY of their gas engine vehicles, EVER!
Nor does my C6Z06 LS7 427 engine anywhere in the GM literature state, "feel free to use a diesel oil since those oils are "heavy duty". I think the Germans at MB would come ****** my AMG from me if I put diesel oil in their hand built AMG V8 as well..............
You can probably put transmission fluid in the oil sump and the engine would run fine which does not mean you should>>.......
Forget Rotella!!!
Last edited by jb78L-82; Jun 19, 2020 at 01:45 PM.
.........A 15W weight oil is perfectly fine for temps over 32 degrees.....78 C3 Owners manual....
Very true, but to my way of thinking, I would think that it's a pretty safe bet that most of the C-3s that are on the road today, are "weekend drivers". Therefore they sit all week, and the oil drains off pretty much everything. Consequently a blended viscosity oil, with a "5W" as it's first number, would be a good thing, since it's initial "cold flow" would get the circulation going quicker.
Very true, but to my way of thinking, I would think that it's a pretty safe bet that most of the C-3s that are on the road today, are "weekend drivers". Therefore they sit all week, and the oil drains off pretty much everything. Consequently a blended viscosity oil, with a "5W" as it's first number, would be a good thing, since it's initial "cold flow" would get the circulation going quicker.
Just a thought..........
I agree that a thinner oil at cold startup is most important for oil flow to critical engine parts quickly. Like I said previously in my Roller cammed L-82 355 I use Mobil 1/EDGE 0W-40 European Formula only since I know the 0W is best for cold start and the 40 gives extra top temp protection. I ran 15W-50 Mobil 1 for years in the OEM L-82 before the rebuild/upgrade in 2014 but I do not drive the car in cold weather. A 15W synthetic weight oil, in my opinion, and experience is perfectly fine in any temperature starting at 32+ degrees.
Tip for all: I always prime my motor by not setting the choke at cold start by spinning it with the starter for 10 second intervals consecutively with 5 second pauses before setting the choke and allowing it to fire.....oil pressure is at 50 PSI before it fires up. Did the same for years with the 15W-50 Mobil 1 before the rebuild. Same for my 10 C6Z06 priming the LS7 427 engine before firing....every time at cold start after sitting for more than a day.
Every car, internal combustion generator, snowblower, lawn tractor engine I own, uses 0W-40 synthetic European Formula (MUCH more robost additive package than standard synthetics) only.....I do not uses any other weight oil and have for years now......
Last edited by jb78L-82; Jun 20, 2020 at 07:23 AM.
Tip for all: I always prime my motor by not setting the choke at cold start by spinning it with the starter for 10 second intervals consecutively with 5 second pauses before setting the choke and allowing it to fire.....oil pressure is at 50 PSI before it fires up. Did the same for years with the 15W-50 Mobil 1 before the rebuild. Same for my 10 C6Z06 priming the LS7 427 engine before firing....every time at cold start after sitting for more than a day..
Agreed. I've done this for decades when starting my Corvettes. Only when I see the oil gauge rise do I pump the accelerator and set the choke. My engine builder said this is good practice and is what he does with his car(s).
GM originally advised you to use certain oils with specific additives BUT those oils have since been taken off the market by the EPA a long time ago so you can no longer buy them.....WHY?....Catalytic converters were mandated by the EPA for CARS and the flat tappet saving additives were removed from "car" rated oils. The converters were being ruined by the oil additives we need for our old flat tappet cam car engines. Taking the additives out destroyed cams and lifters. All due to the newer CAR oil formulations.
Diesel trucks always required even higher heavy duty oil performance standards than cars ever did. EPA did not require catalytic converters on diesel trucks for many years SO the good oil additives were still available in the diesel truck rated oils. Use the diesel oils and you still got the flat tappet additives. Also very tough oil. This was true for some time.
More recently, EPA started requiring tighter emissions standards on newer diesel trucks....SO....the latest diesel truck oils have removed most of the good additives we were using to save our flat tappet cams in cars. The diesel truck oils are not as good as they used to be for our flat tappet car engines. Still good heavy duty lube but does not have all the good flat tappet cam and lifter additives like it used to.
I stopped buying Diesel oils and started buying off-road car racing oils with long interval oil change additives.
GM originally advised you to use certain oils with specific additives BUT those oils have since been taken off the market by the EPA a long time ago so you can no longer buy them.....WHY?....Catalytic converters were mandated by the EPA for CARS and the flat tappet saving additives were removed from "car" rated oils. The converters were being ruined by the oil additives we need for our old flat tappet cam car engines. Taking the additives out destroyed cams and lifters. All due to the newer CAR oil formulations.
Diesel trucks always required even higher heavy duty oil performance standards than cars ever did. EPA did not require catalytic converters on diesel trucks for many years SO the good oil additives were still available in the diesel truck rated oils. Use the diesel oils and you still got the flat tappet additives. Also very tough oil. This was true for some time.
More recently, EPA started requiring tighter emissions standards on newer diesel trucks....SO....the latest diesel truck oils have removed most of the good additives we were using to save our flat tappet cams in cars. The diesel truck oils are not as good as they used to be for our flat tappet car engines. Still good heavy duty lube but does not have all the good flat tappet cam and lifter additives like it used to.
I stopped buying Diesel oils and started buying off-road car racing oils with long interval oil change additives.
I'll just add this "tidbit"....STP oil treatment labels now proclaim that they contain ZDDP, "to provide added anti-wear protection".
