VikingTrad3r

title says it all. could an l98 just use mobil one and then be protected against oil heat the same as an lt1.

opinions?

c4cruiser

GM went to a full synthetic 5W-30 Mobil 1 with the introduction of the LT1 engine. The engineers didn't retain the L98 "oil cooler" to save weight and the full synthetic oil had the ability to handle higher oil temps without the need for a cooler.

Using a full synthetic in an L98 engine will help with higher oil temps but the Corvette L98 design used the oil cooler to help with oil temps as it didn't use synthetic oil. Nothing at all wrong with using a full synthetic in that engine. I ran Mobil-1 5W-30 in my '87 for track use and autocross and I never saw oil temps above 210.

Was it the synthetic? Hard to say as I used a 180 thermostat and had removed the A/C condenser to get better airflow thru the radiator. Coolant temps usually ran 185-195 on days were the air temps were around 100 and track surface was close to 130.

So I would say that, yes a full synthetic will be a help with lubricating the engine where high oil temps might be encountered. For general street use, it's not really necessary but lots of people here use it. One thing that you do get with a full synthetic is more miles between oil changes.

antfarmer2

It is better oil as the price reflects but I would let it drain over night for the change.

2airtime2

I don't think the oil is going to reduce the engine temp of a L98, nor keep it from overheating.


If you develop a problem with the L98 where it overheats I believe the synthetic oil won't break down and will provide protection everywhere it flows.

VikingTrad3r

Thanks guys, I acquired an 86 manual gearbox and i intend on tracking the car this season. it did not come with the oil cooler and im trying to sort out the best way to protect the engine during track days. for starters, i'll use mobil 1 for track days and might find an oem L98 oil cooler and install it. (if that is even possible not sure if it will be provisioned for it).

VikingTrad3r

ant is there something about mobil one that you recommend this or is this for all oil changes?

Joe C

obviously, the more (old) oil you can remove, the better off you are, however, a normal drain (say 10 minutes or so, warm engine) will get most likely a +99% drain. I wouldn't get carried away too much with the drain times, besides, you will never get a full 100% drain - period!

FWIW, I've recently switched to 10W30, high mileage, mobil 1 for my (157K mile) 85. I was a long time Castrol GTX (10W30) user, but after some discussion about ZDDP on the forum, I though it couldn't hurt anything by going to a high mileage full synthetic. BTW, I do have the factory oil cooler.

antfarmer2

I always let it drain then rinse with a half a quart or what ever I will have left over. On a synthetic oil change I will let it set over nite if possible.

VikingTrad3r

joe, i love your mileage. really. i just love getting every ounce of value out of equipment. did you find that going to the 10w30 gave any compression or oil pressure back?

thnx ant, i can give that a try and i will switch bins when i leave and see how much stuff is in there in the morning. i bet it will be half a cup anyway.

antfarmer2

Thanks let me know how much is in there never did that.

DGXR

Synthetic won't help any existing overheating issues but synthetic will last longer and handle higher temperatures better than conventional. Since you are tracking the car, you might consider a slightly heavier weight like 10w40.

All motor oils (including Mobil 1) can be mixed together, no issues with compatibility, and no worries about a few ounces remaining in the engine to be mixed with the fresh oil. This is normal. Some people mix different weights, different brands, synth and conventional... never heard of anyone having an issue traced back to mixing oils. If you have the time to let it drain overnight, that's great. But as noted above, a 100% oil drain is not possible short of disassembling the motor. In trying to get 100% clean oil, I have seen some people change the oil, run the motor a few minutes, then change the oil again. This is a huge waste of oil unless the clean stuff is used for something else.

mickey5

Based on past forum threads about changing an old engine from dino to synthetic; there was a lot of concern regarding oil leaks with the change over. If GM didn't change over the L98 recommendation I'm leaving well enough alone. I'd rather cruise than clean up the garage floor and replace gaskets.

VikingTrad3r

you are right it will expose leaks.

in my case, im tearing the topend down to reseal it and pulling the pan to inspect the bottom end so ill have a tight new unit with hylomar assisted sealing.

I am using his car on the track which is the reason why I am concerned about the overheating. Here is a very interesting video, I never put too much stock in the marketing that mobile one was any better than the others. But I have to say after seeing just the simple exercise I am impressed.

https://youtu.be/uQ_vxdO_9nc

cv67

Mobil 1 is still good but it isnt the stuff it used to be years ago

If its a track car then a good oil cooler and yes syn probably the way to go. Gaskets cheaper than a motor

Tom400CFI

I think any decent oil, with any decent cooling system should be better than good enough. I think any synthetic offers better protection, M1 included. RPM creates heat in the oil and the L98 revs lower than the LT1...Good oil + functional cooling system= A-O.K.

That test is interesting...but it's testing a criteria that you don't care about.

aklim

Well, you have to get THIS and the correct hoses. IDK what you have for hoses. Mine goes into the block at one end and the other into whatever it connects to.

aklim

I have my doubts. All my cars are switched over and I haven't found one yet. Before the switch, I get a good sample and send it for testing and send the synthetic for testing too. So far, I have been told that I can extend the change enough to justify the cost plus labor.

whalepirot

When I first switched to M1 in 1956, I found the oil pressure dropped alarmingly, at idle. All manufacturers switched to lower viscosity oil to improve CAFE.

MatthewMiller

Right, but to clarify: he is asking about whether a full-synth oil is better protected from "overheating," not whether the oil will protect the rest of the engine from a coolant overheat. Real synthetic oils typically have better resistance to breakdown from high-temp/high-shear conditions (HTHS), which are a lot of what's encountered during repetitive lapping and other high-powered events.

Oil coolers are generally a good idea as long as your oil isn't running too cool (probably want to see at least 180*F or more). I have a Setrab cooler in front of my radiator and I need to keep it blocked off from airflow except for actual track events, or the oil runs too cool. But I doubt the factory L98 cooler will ever get close to keeping it too cool.

BTW, I agree with Joe C about the 10w30 High Mileage M1 for track events. It has an A3 rating with very good HTHS specs. I am running 5w30 High Mileage for the cooler weather, when I know I won't be running any track or autocross events.

VikingTrad3r

yeah matthew nailed it. my car isnt overheating the cooling system works fine. but ***** out track days elevates the temps of the oil and i was inquiring about mobile one protecting better and not breaking down in the super high temperatures.