So I've had my '91 auto about a month now and I am about to change the oil. I noticed in the upper corner of the windshield a sticker from Texaco saying the oil that was put into it was 10W30 syntheyic.
I've heard that the L98 engines will usually leak oil if you put syn in.My question is: Should I go ahead and use syn again since according to the sticker it has been nearly 3000 miles and about 8 months since the last change?
I currently have no leaks, oil pressure is good, and looks really clean on the dipstick.

 

I picked up my '88 with 96k miles and switched to full synthetic; that was 50k miles ago and still no leaks nor increase in usage.

 

Go with what was in there. You might also want to think about Mobil 1. I think thats what the owners manual calls for. If you change your own oil, Mobil 1 can be purchased at Walmart in a five gallor container for $19.95. Get a new filter and you'll be good to go.

 

I'm no expert on oill, but I can say that my '90 Corvette has nearly 89,000 miles and it doesn't use a drop of oil. Not one drop. (I just knocked on wood.) I am told it's always had 5W30 Mobil I. That's what I continue to use when I change oil.

My Nissan truck has 300,000 miles on it, and it does not use a drop of oil. It's always had 10W40 Pennzoil. My dad always told me that if you ever start using an oil or viscosity that's different from what your engine has been using, then the engine is more likely to start using oil.

On the other hand, my 2003 Caravan has been using oil from the get-go, and I bought it brand new. -- Eric

 

myth's

 

i read somewhere that chevy began recommending syn oil when they discontinued the crazy oil cooler(just finished replacing the hoses)which allegedly reduced oil temps up to 20 degrees. one or the other may be needed to stop break down caused by thrashing and heat build up due to the wrap around one piece hood.

 

i read somewhere that chevy began recommending syn oil when they discontinued the crazy oil cooler(just finished replacing the hoses on 85)which allegedly reduced oil temps up to 20 degrees. one or the other may be needed to stop break down caused by thrashing and heat build up due to the wrap around one piece hood.

 

when i switched the syn, i noticed a small leak. i think it is coming back from the intake. ppl say it is better for the motor, and is good for around 5chp. but i would use it, like a say it is a small,small leak.

 

Model year `92 is when Vettes began using synthetic oil (from the factory with the new LT1 engine). With the exception of the ZR1s, the oil coolers were dropped from base engine Vettes.

I also use Mobel 1 synthetic in my `91 L98.

 

Agreed. Myth. Don't draw generalities from someOnes bad experience. Any older motor (re: worn out) will leak to some extent if thin enough oil is put into it. It's leaking Anyhow (same logic applies to "using" oil - past the rings and down the valve guides), just not as Fast with thicker fluids behind the seals. Stuff ages and wears - including seals, and rings, pistons, cylinder walls, bearings, etc.

Oil leaking Out of the motor past the crank seals (or dead oil pan, valve cover or intake gastets) isn't a big deal as long as the level is checked and maintained. Messy, perhaps, but not a real problem - fix the offending seal or gasket and the problem goes away.

Oil being Consumed during combustion, weather due to poor ring seal or to worn Intake valves/guides/seals (exhaust valve issues will not result in oil useage - only in the annoying puff of blue smoke when the motor is started up) is another matter. More expensive to fix mostly, and more work. Still not an issue as long as the level is maintained (do NOT let the thing run out of oil!)

The REAL thing to worry about is the oil pressure. As long as the pump will maintain sufficient oil pressure through the worn clearances in the lifters, bearings and etc. then the oil is thick enough. Too low a pressure means no oil making it all the way up the pushrods to the top of the valvetrain (rockers) - and early (well - earlier than really necessary) valve guide death. Also means not enough oil splashing around in the crankcase to keep the cylinder walls happy. Synthetics, because of their (normally) more consistent viscosity across temperature ranges, are better here than dino oil - they do not "thin out" as much when they get hot.

Enough of that. I run the Amsoil 0w-30 (yes - zero w) in my 200,000+ 1985 L-98. As far as I can tell the bottom of this motor has never been apart. Off idle it pulls 40 -45 psi of oil pressure. It holds about 20 psi of oil pressure at a hot idle of about 560 rpm. Just about as low as I want to see it get - any less and I'd have to do Something about it - probably time to replace (or rebuild) the bottom end. Yes - it leaks some. I have replaced the front seal and the intake manifold gaskets (although it had been off before, along with the heads - the idiot before me apparently didn't have a clue how to build a small block chevy...). The oil pan remains dry - only the rear main seal is an "issue" - with a slight leak obvious - Not bad enough to justify the work to replace it.

The cold weather and wear resistance benefits of Good synthetic oils far outweigh the "bad" news - I would not consider ever running anything else. (shoot - I use mobile 1 in the Lawnmower!).

 

What do you expect, It's a Chrysler product!!

 

As was said earlier, the benefits of synthetic far outweight the bad experiences some people have with them.

Almost all new performance (and some non performance) cars come from the factory with Mobil 1 synthetic. This includes Corvettes and Porches. When we got our new Hemi Ram (yes a Chrysler product) it came stock with synthetic in the engine, trans, and differential. I have no complains with that truck. The engine runs like a dream .

Sort of like sythetic oil . . . Chrysler IMO has overall decent products . . . dont let a few bad experiences ruin it .

On that subject, Chrysler did some smart things when taking ownership of Mercedes. They now incorporate a lot of Mercedes technology in their vehicles. Like the new 300's use Mercedes transmission and suspension. I have heard nothing but good things about that car.

Anyways . . . check out Mobil 1's site. They discuss the use of synthetic and try and dispell many of the myths surrounding its usage.

 

 

I have used synthetic in mine since the 2nd oil change, it leaked beforehand, leaked the same afterwards.

Synthetic have detergent packages that tend to break away contaminants and deposits inside the engine, which is good for the internals, but tends to make gasket/seals show their age because those deposits fill gaps and holes in the seal.

I can deal with leaks if it makes my engine last another 50K.

 

I used Mobil in my 89 from 49K miles to 68K miles, when I developed a very small, and common, intake manifold oil leak on the back side. I don't think the synthetic caused the leak and will continue to use the synthetic. I think it is better all the way around.

MTCW Bob

 

THANKS Y'ALL
I am going to go ahead and grab up some Mobil 1 from Wal-mart and a K&N filter and have a go at it.

 

I have been running AMZOIL Gold 20/50 full synthetic for over 50000 miles now. No leaks, no oil consumption. Pressure at hot idle around 60 psi

seeya

 

You won't be disappointed. Go for it!!!
You might want to have your first batch analysed to get a benchmark/base number on oil and an evaluation vis-vis the wear on the engine. I use www.blackstone-labs.com


MTCW Bob

 

Go for it, but I think you will find Mobil 1 is not a full synthetic ever since they got into a patent fight and lost it to Castrol.

Even Dino oil is great if you change it every 3000 miles

seeya

 

Beat me to it!