Oil recommendation for a 1986 L98 Corvette, please

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Hello.
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Here's some background:

1. What kind of vehicle you have
Chevrolet Corvette 1986 L98 ie. 350 TPI, 65 tml

2. What your owner's manual says
Sorry, no manual, just 5W-30 info on oil cap

3. Where you live
Northern Europe, will run it only in the summer in temp range of 40...90F

4. How you drive (easy? hard? fast? slow?)
Easy driving around town and highway, some blasts trough the twisties and a relative easy track day or two in the season.

5. What your daily drive is like (short trips? long trips? city? highway?)
Mostly short trips in the city/highway. Also longer highway trips on vacation when touring.

6. Whether your car has any known problems
No engine problems. Previous owner has used Kendall GT1 5W-30.

--------------------------------------------------------------

Right. I could use some advise on what oil to use. I'm switching away from previous owner's Kendall because it is not available easy and it costs more than Mobil 1 0W-40.

Over here there are couple of 5W-30 oils available on the shelf but they tend to be Long life types. These are such as Mobil ESP, Castrol Edge, Valvoline Synpower, Shell Helix and some local brands such as Teboil Diamond and Neste. Also GM 5W-30 Longlife is available easily.

If you recommend me to stay with 5W-30 is there a brand you would recommend for me? 5W-30 oils such as Redline and Royal Purple are not available here.

It seems that the most common weight over here nowadays is 5W-40 and just about any of the bigger names have their products available in this weight such as Shell Helix in several types, Mobil Super 3000, Castrol Magnatec etc. Also some brands in 0W-40 weight, too.

Given the background above and info on what is available (just few listed) I'd like to ask whether:

- I should stick with the 5W-30 -> which one?
- switch to 5W-40 -> which one?
- what about 10W-40? Redline and Brad Penn available

I fear I'm overthinking this matter ie. does the brand/type/weight matter at all for this old engine?

Thank you for your patience.
blush.gif
 
Originally Posted By: Finn
Hello.
cheers3.gif


Here's some background:

1. What kind of vehicle you have
Chevrolet Corvette 1986 L98 ie. 350 TPI, 65 tml

2. What your owner's manual says
Sorry, no manual, just 5W-30 info on oil cap

3. Where you live
Northern Europe, will run it only in the summer in temp range of 40...90F

4. How you drive (easy? hard? fast? slow?)
Easy driving around town and highway, some blasts trough the twisties and a relative easy track day or two in the season.

5. What your daily drive is like (short trips? long trips? city? highway?)
Mostly short trips in the city/highway. Also longer highway trips on vacation when touring.

6. Whether your car has any known problems
No engine problems. Previous owner has used Kendall GT1 5W-30.

--------------------------------------------------------------

Right. I could use some advise on what oil to use. I'm switching away from previous owner's Kendall because it is not available easy and it costs more than Mobil 1 0W-40.

Over here there are couple of 5W-30 oils available on the shelf but they tend to be Long life types. These are such as Mobil ESP, Castrol Edge, Valvoline Synpower, Shell Helix and some local brands such as Teboil Diamond and Neste. Also GM 5W-30 Longlife is available easily.

If you recommend me to stay with 5W-30 is there a brand you would recommend for me? 5W-30 oils such as Redline and Royal Purple are not available here.

It seems that the most common weight over here nowadays is 5W-40 and just about any of the bigger names have their products available in this weight such as Shell Helix in several types, Mobil Super 3000, Castrol Magnatec etc. Also some brands in 0W-40 weight, too.

Given the background above and info on what is available (just few listed) I'd like to ask whether:

- I should stick with the 5W-30 -> which one?
- switch to 5W-40 -> which one?
- what about 10W-40? Redline and Brad Penn available

I fear I'm overthinking this matter ie. does the brand/type/weight matter at all for this old engine?

Thank you for your patience.
blush.gif


You're at home here ,most of us agonize over this stuff.
 
Any of the 5W-30 you mentioned would work well.

I'd go with the Edge or the Synpower if it were me....
 
Hello!

Update on this matter after almost full driving season (which is about to end soon).

I went with Redline 5W-30 which was available not locally but got that fairly easy. Pressures have been OK, around 450 kPa when doing 60 mph in OD engine fully warm. Warm idle op has been from 250...300 kPa depending on outside temperatures.

What I have noticed is that the engine does consume this a bit. It does not smoke or leave a puddle, just vanishes. Considering the mileage I do each season the usage is not a big issue but I'd still would like to switch to 5W-40 because of it.

I thought all TPI engines have roller cams but that is not the case as they came in -87. Mine is an -86 with iron heads and this has a flat tappet cam so apparently I would need an oil which has heeps of ZDDP, right?

Would off the shelf fully synthetic 5W-40 spiked with extra ZDDP do the trick?

Suggestions are welcome, please.
 
Last edited:
Originally Posted By: Finn




Would off the shelf fully synthetic 5W-40 spiked with extra ZDDP do the trick?



How about Redline 5w40? I believe it has a pretty high amount of ZDDP.
 
Thanks guys.
cheers3.gif


Unfortunately the Rotella is not available over here, all I see is Shell Rimula such as Rimula R6 in 5W-30 and 10W-40 and Rimula R5 in 10W-40.

How about Mobil 1 Delvac 5W-40 - it's widely available and stocked just about everywhere? I read some source that it has P almost 1400 and Zn 1800. Can this be true?
 
Originally Posted By: Finn
Hello!

Update on this matter after almost full driving season (which is about to end soon).

I went with Redline 5W-30 which was available not locally but got that fairly easy. Pressures have been OK, around 450 kPa when doing 60 mph in OD engine fully warm. Warm idle op has been from 250...300 kPa depending on outside temperatures.

What I have noticed is that the engine does consume this a bit. It does not smoke or leave a puddle, just vanishes. Considering the mileage I do each season the usage is not a big issue but I'd still would like to switch to 5W-40 because of it.

I thought all TPI engines have roller cams but that is not the case as they came in -87. Mine is an -86 with iron heads and this has a flat tappet cam so apparently I would need an oil which has heeps of ZDDP, right?

Would off the shelf fully synthetic 5W-40 spiked with extra ZDDP do the trick?

Suggestions are welcome, please.


I have an 88 IROC TPI with the roller cam. It also "consumes" some oil but does not leak nor smoke. Since I do have a roller I've been using regular M1. If I had a flat tappet cam, I'd probably run an HDEO.
 
Hello!

As it happens I have the old flat tappet L98 on the floor and a master builder is building me a mild 383" with forged Scat crank and rods, forged Wiseco pistons and AFR 180 heads. This is built on 87-> roller cam block so no more worrying about the lobes. The engine will be mild ie. 350...375 hp but with 475...500 lb-ft.

My question is as follows:

I have noticed that when the power levels rise from the original on built motors also viscosities people use tend to rise. Is there any need for this as the clearances are the same? Several of my buddies seen to run 5...10W-40 or even 15W-50 in this type of built "modernish" late 80s to mid 90s small block Vettes. Is there any need for this or would they do just fine with a quality 5W-30 viscosity oil?

I'm a bit puzzled as the builder said he'd run this new engine with 20W-50 Pennzoil GT.
 
You just couldn't resist modifying your engine, could you?
smile.gif

As long as bearing clearances are being held within factory specifications, any good quality 5w30 would work in your mild 383.
GM specifies 5w30 for all their LS-series engines, and they make more power than your 383 will. Why not stay with Redline, or is it too difficult to find over there?
If you are keeping the oil cooler on the engine, and the oil temp never gets over 140C, I don't think there is a need for a 40 or 50-weight.
I have done track days with my '85 L98 since 1991, and used 5w30 for all but one year, when I used Castrol Syntec 5w50. When I saw that piston deposits seemed to be increasing with Syntec, I switched back to GTX 5w30. Then last year I switched to Mobil 1.
 
Originally Posted By: A_Harman
You just couldn't resist modifying your engine, could you?
smile.gif


Sorry, nope.
grin.gif


That's what I've been thinking myself ie. if the clearances are within say -86 spec then std 5W-30 should do. I'm going to talk with him about this a bit more when we start the build. Parts should arrive within a couple of weeks.

Redline products are somewhat a special order thing but nothing that I could not overcome. Other 5W-30 oils are widely on the self such as Pennzoil, Castrol SLX, Valvoline Synpower, Mobil ESP, Shell Helix Ultra/Extra etc. For some reason I would prefer Mobil 1 0W-40 over LL ESP but I don't know if it would be a blasphemy to put 0W-40 in a Gen 1 SBC.
whistle.gif
 
Originally Posted By: Finn
Hello!

As it happens I have the old flat tappet L98 on the floor and a master builder is building me a mild 383" with forged Scat crank and rods, forged Wiseco pistons and AFR 180 heads. This is built on 87-> roller cam block so no more worrying about the lobes. The engine will be mild ie. 350...375 hp but with 475...500 lb-ft.

My question is as follows:

I have noticed that when the power levels rise from the original on built motors also viscosities people use tend to rise. Is there any need for this as the clearances are the same? Several of my buddies seen to run 5...10W-40 or even 15W-50 in this type of built "modernish" late 80s to mid 90s small block Vettes. Is there any need for this or would they do just fine with a quality 5W-30 viscosity oil?

I'm a bit puzzled as the builder said he'd run this new engine with 20W-50 Pennzoil GT.



ask him if he is clearancing the crank, if he is increasing rod clearance then you will need a thicker oil but if the bearing clearences are stock, and the block is not being grouted there is no need to run a 20/50.
the fact that some l98s came with flat tappets is news to me, i have never owned a vet but i thought they were all hydraulic roller. with a mid lift flat tappet i would run the an oil with at least 1200 ppm zinc and maybe run a 5w40 if you plan on ragging on it alot. the delvac you mentioned falls in the category
 
I have a full tilt roller small block with about 550 crank hp.

We run 0W-30 in it. Recommended rev limit is 6800-7200 rpm.

No way do you need that 20w-50
 
Thx guys. I'll keep record - as will the builder too - of the clearances.

Last question on the subject:

Vettes run hot. Well, the thermostat is 195F so basically they run normal hot. Would you run short oil change intervals with mineral oil such as 5W-30 Pennzoil in it or would you still prefer semi or full synth?
 
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