Ok guys here is the scoop. I get my maintenance done in a Corvette only shop. They have been in the business for over 15 years and have always been very honest, that I assure you all. I purchased an 87 back in November with 111,500 miles on it. I had no idea what types of oils were used on the car for tune-ups.

When I called the shop spoke to a good friend he recommended to use regular oil and change every 3000 miles. Here is what he told me.

1. You do not know what type of oil the previous owner used so your best bet is regular 20/50 oil.

2. Synthetic oil is man made with additives that are great for newer cars but bad if used on older cars that were previously had regular oil.

3. If an older car had regular oil and with such high miles you add synthetic you may potentially expand the oil seals and get leaks on the car.

4. Tested by others if you grab an oil seal and put it in a glass with synthetic you can see the rubber seal expand an eventually break as compared to putting and old seal in a glass with regular oil and nothing happens to the seal.

5. It is harder for synthetic oils to reach your entire engine on morning starts or long periods of shut off time as compared to regular oil that runs through the engine faster.

6. He insist that for my car is better regular oil than synthetic, for cars that the engine was conditioned to synthetic then it is better to stay on it.

Can someone help? I am currently using Mobile 20/50 for high mileage vehicles or should I just switch to synthetic?

 

This topic has been........nevermind, just switch to synthetic and don't look back.

 

Same arguments each time, run Mobil 1 or another synthetic in your engine if you want it to last as long as possible.

1. Too thick to run.
2. Its not entirely man-made, but does have additive packages. These additives clean out the engine, resulting in ZERO sludge in your oil pan. Whereas that 20/50 is gonna drop TONS of sludge in the pan.
3. You get leaks from the additives which break up sludge that might be hiding in crevices at the gaskets. It is true that you can get leaks from synthetic switchover, but its not from the oil eating away your gaskets.
4. Id have to know the details of this experiment, but on our engine i would call BS. You cant go by an experiment without knowing the details.
5. Its easier for them to reach everything.
6. Up to you

Synthetic was introduced because GM deleted the oil cooler, which actually does nothing IMO, it acts more like an oil warmer in cold weather. But the damned engine still runs hot with it, so its not really cooling anything off.

There will be ZERO sludge in your pan after Mobil 1 has been in there, while dino can sludge up everything.




[Modified by vader86, 1:47 PM 2/13/2003]

 

I disagree. There is no need for synthetic in an 87. Plus you do not know the history. I have never had any problems with regular old 10W30 motor oil from Mobil. It's what i use in everything. If i had a newer vette without an oil cooler i would use synthetic. As it is i have a 91 vert with the L98 engine and i change the oil every 4-5K miles. So far she has 98,000 miles and doesnt use a DROP between changes, and i drive it hard here and there it is not babied. Why chance creating problems. I would go with 10W30 the regular stuff and have that be that. I have though of switching to synthetic but don't see any real benefit at this stage in the game. if it ain't broke don't fix it. The L98 does not need anything other than Dino oil. JMHO but an experienced one.

 

Point 1. 20/50 is a little to thick to be running
2 Synthetic oil is not man made. It is all in the refining of the base oil to make the oil molecules uniform in size http://theoildrop.server101.com/cgi/...c;f=4;t=000042
3 It may cause leaks but not from harming the seals. Synthetic oil has better detergents that clean sludge away and may cause leaks were old seals have broken down and the sludge was stoping the leak
4 Never heard of this
5. Synthetic oil will reach internal engine parts faster due to its low pour and pump rates.
6. I would say thats up to you but I would have no problems myself. I bought an old Ford Pickup with 140K and switched to Synthetic oil. No new leaks or problems.

 

:iagree:



[Modified by FlyboyZR1, 12:50 PM 2/13/2003]

 

:iagree:

Next time you're under the hood, pull off the oil fill cap and see if you see a brown varnish and or sludge. If so, a switch to synthetic oil will clean all that away. The sludge will disappear fairly quickly(~1k miles), while the varnish will take quite a bit longer to be removed. I purchased my vette with 62k miles on the odometer, and promptly switched to mobil1 5-30. There was no visible sludge when I bought the car, but there was some varnish. ~8k miles later, no more varnish, just clean metal.

Synthetic pours better when it is cold, but there are some dino oils that are approaching the lesser synthetics in performance. They are more resistant to heat and extreme pressure conditions.

If I were you, I'd drop the ~$30 on some mobil1 and see if it gives you any problems. If you start leaking, or burning a lot of oil, switch back to dino. I would recommend 10-30 or 10-40 for your higher mile engine.

Good luck with your decision

J :seeya

 

:lurk:

 

I run Mobil 1 in everything I own including the lawn tractor. Also i have purchased many high mileage vehicles and switched to Mobil 1 with no ill effects. If your really worried and don't know what to choose, buy Mobil semi-synthetic and have it both ways. Whatever you use, changing it regularly is whats important. good luck, Dan :sleep:

 

MOST of his arguments make sense, except for this one

5. It is harder for synthetic oils to reach your entire engine on morning starts or long periods of shut off time as compared to regular oil that runs through the engine faster.

That really raises the :bs with me. That's the whole point, synthetic flows better at all temperatures. If you let a car sit long enough to let all the oil drain into the pan and fire it up you will want something that's gonna get there fast, hence the synthetics which will still flow very well at VERY cold temps. The only logic I can see in this statement is if he's just saying that the non synthetic doesn't drain back down into the pan as much. In which case this can hardly be a good thing, sure there is still oil there, but if it's so thick that it didn't drain into the pan it's hardly gonna be doing you any good.

If you ever take a motor apart that's run mobil 1 synthetic vs a motor that has run dino oil it will make a very firm believer out of you. You won't believe your eyes at how clean the mobil engine is even when compared to "clean" dino oil engine.

On the flip side of the coin there is always the possibility of oil leaks. A friend of mine bought a 95 Z-28 with 100k miles on it. The previous owner used dino oil and never changed it regularly. We pulled a valve cover off one time and it was just plain NASTY under there. In any case it didn't leak oil when he bought it, or just a little drop every now and then. Now about a year later after running Mobil 1 it's leaking oil from EVERYWHERE. I'm pretty sure that if it's meant to hold oil on his car, it's leaking. Now this could just be coincidence as well, you'll have to make that call on your own. I think it's because of Mobil but I think it's also in combination with how badly the car was abused before as well. A properly maintained dino oil engine might not suffer the same fate.

Only way to find out is to put synth in there and find out. You absolutely won't hurt anything, you just might develop some oil leaks.

 

I think synthetic was a GM standard in 92 (My year). I know one reason was to eliminate the need for an oil cooler. I have to admit since the Ed wright chip and the full synthetic my engine temp never gets past the first hash. And the oil temp take about 15 to 20 min to even register a temp!!! I am not sure if that is good(So I don't press her until she has a nice oil reading). But I know that my car runs in extreme heat conditions (Texas) Nitrious and AC it only adds to the heat. I love the synthetic, but it may not be for everyone. I know that regular oils heat up much quicker.... If this is the desire effect go with regular, if you want better cooling and longer wear with less buildup go with synthetic.

 

:withstupid: i switched to Mobil1 about 2 months ago. my car had been driven by me for about 8000 miles on regular oil and who knows how long by the previous owner. i switched and have had 0 leaks and with all the positive aspects of the synthetic, i think you should at least give it a try, it would be better...if it leaks, switch back, can't hurt, maybe get you a spot on your driverway or something, that' about it :D

 

Thank you all, I will try Synthetic this weekend and see how it works out. I
know the topic has been posted over and over but my mechanic scared me so
much that for a moment I thought I would actually damage the engine badly.
Also, I know this is coincidental but I had a 94 Z28 that blew a head at
105k and I used Synthetic oil (oil changes every 3000 or so) since I
purchased it new in 94. So that plus my mechanic just scared me.

 

While I don't understand/agree with many of the points in this thread, let me just say that I would do as your shop friend says - stay with the regular oil.
At some point - if you keep the car a long time and pile the miles on it - and the engine has be be pulled/rebuilt - then go with the Mobil 1.
Just my 5.7 cent opinion.
:seeya :steering:

 

Synthetic is definately the better way to go.

You don't say what weight you are going with, but I am pretty sure the GM recommended weight was either 5w30 or 10w30. If the previous owner was using 20/50 it may have been because the car was burning oil with a lighter grade so be sure to monitor your oil level for any consumption until you see what happens.

Let us know what happens. All of us would like to hear first hand some actual experence about changing to synthetic, hopefully it will be good.

 

be careful. People are missing an important part here. If you were to switch to synthetic and develop leaks as a result of the oil cleaning the engine out. You can't just switch back to dino oil and expect everything to be fine. The leaks are there now and any oil will leak through them. You may be able to switch and have no problems but why chance it. If you have a problem it will be one that is permanent until you pull the engine apart and fix it. You need to keep this in mind. The L98 runs fine on dino. I use 10W30 always have and am about to turn 100,000 miles. I don't use a drop of oil between changes which are spaced out 4-5K miles. I think thats a good track record. Stick with a good Dino oil, dont chance creating leaks and spend the money you save on regular oil on something more fun for your vette. If it is fine now with Dino, it will be fine into the future. Synthetic is not some kind of magic juice, you even had firsthand experience with you camaro, you used it regularly and still had problems. If it ain't broke DONT FIX IT. :cheers:

 

I agree with Robertpel9.
I've been using Pennzoil 20W50, year round since 1993. (10W30 prior).
Only leak I ever got, was a rear main seal, and that was corrected when I did my first rebuild in early '93.
I'm sure there are pluses using Synthetic versus Regular Oils, but from what I've been able to observe over the 17 years I've owned this Vette...as long as you change your oil on a REGULAR basis...sludge will NEVER be a problem.
As the original owner of my '86...and seeing the inside of my oil pan on 4 occassions over the years...no sludge whatsoever, and I change the oil out every 3K.

 

I don't disagree that one option is to stay with good grade of dino and change regularly.

For what it is worth I personally have two OK experiences changing from dino to synthetic.

First my 1999 Toyota Sienna has the V6 which has been reported to have a hot spot causing sludging & since this vehicle sees a lot of highway driving I changed to Mobil 1 5W30 at about 45k miles. It now has about 53K with 1 oil change, no problem.
Second my 1991 Toyota PU with 4 cylinder, changed to Mobil 1 10W30 at 104K miles. No problems so far. By the way I put Mobil 1 gear lube in both the transmission(5 spd man) and differential at about 80k miles, it noticeably improved the shifting.

 

I use Mobil 1 Multi-Vehicle Formula 10w-30 in my '85. I noticed the engine runs cooler with the synthetic. Switch to the synthetic. look at it as engine insurance. Oil is cheaper than a new motor! :chevy

 

I had my mind made up and then some of you bought up a good point about synthetic. I will contact a few Corvette shops around and see what they say. As I see it,, it will be a 50/50 chance and like some say why fix something that is not broken. I can assure you all that I change my oil every 3k sometimes even sooner. I will do my homework on this and will revisit this issue in a couple of weeks.