norton77

Hi

I have a 1991 coup with 304,000 miles with original engine
valve seals replaced only, good compression, inside cylinders
looked good...

Used moble 1 10w30 synthetic always, and so the original owner.

N

TorchTarga94

1994 with 103,000. I use Mobil 1 10-w30 full synthetic high mileage. Works like a charm!

HlhnEast

JrRifleCoach

This used to be a sure-fire statement for the mods to go on Red Alert.

I always like the posts where the guy said . . . . .

Paul Workman

The API rating "SF" was in vouge at the time that pre '87 flat tappet motor was new, and the ZDDP content was in the neighborhood of 1200ppm. But, today that ZDDP level for contemporary "SN" 10W-30 (or whatever the manual called for back then) is about 2/3s of what it was in 1985. Ignorance is bliss, and I was ignorant until the day came when...

My wife's flat tappet '69 L46 (350/350) had been on a diet of brand name API "SM" oil when the cam went south, and took the bearings and oil pump with it. Now that it has just passed the break-in period on the rebuilt motor, oil is going to have to be "SF" equiv or bust!

Bottom line: ZDDP levels in off the shelf API "SN" is significantly less than it was in in 1985. Those that blindly hold up the user's manual of an 80s Corvette as a basis for oil selection may just be ignorant of that fact. I invite y'all to do you own research on it, and draw your own conclustions.

I always do an when someone testifies to the mileage they have run up "with no problems". Yeah? Maybe so, but tell me how you know there's "no problems"! By the time there is evidence of a problem, e.g., lost power, running "odd", babit in the oil, rod knock, etc, the damage was done a long time ago.

To those that faithfully hold up the owner's manual as the bible are suffering from a serious education deficit! And, for them especially...

YOUR (their) MILEAGE MAY VARY!

For what it's worth...

P.

Ackman70

Amsoil 5W-30 synthetic in my '93 & '94.

http://www.amsoil.com/storefront/asl.aspx

dukeallen

I haven't used dino since I ran out of dino's to shoot, myself, and squeeze the oil out by hand.

mickey5

Sorry, the L98 is hardly an engine that would require a synthetic oil, engines have to be built to use synthetic. Sure you can use it in anything, but if they don't design it that way, why use it?

Now back to PR&C.[/QUOTE]

Thanks for the insight...since I've driven the 90 vert for 22 years with no engine work except for 2 injectors I'll leave well enough alone and stay with the maintenance program and dino thats served so well. Here's hoping for another 22.

Frizlefrak

No, now that would be humor causing that.

VETTEHIGH

Royal Purple..........

cv67

Agreed, a low rpm motor needs special super duper oil for what reason?

ch@0s

Yup here is what ya need

Alan777

I don't think anyone is claiming the L98 NEEDS synthetic...

hogsnvettes

Yes, but if someone wanted to take advantage of reduced friction and lower oil temps, there are synthetic oils that are designed for older engines.

'95 Coupe with 117K. Normally Amsoil 5W30 but tried 0W30 this winter. No leaks except in the radiator.

FOURSPEEDVETTE

It's all we need to use in our early C4's. If we're not out beating the sh-t out of them or racing them at very high temperatures, it's not neccessary to use sythetics in the early C4's. I don't have time to go out and read all the lab tests and trust in all the stats and figures on oils that someone else says is better. I use what I've always used with absolutely no problems over the years in my many "special" cars. As I said. I had new gaskets and everything was tight as a drum and dry in my 85 until I tried full synthetic. It leaked at the valve covers after one day. I drained it out immediately, and without tightening anything, I filled it back up with conventional oil and the drips stopped right away. It's been dry ever since.

C66 Racing

The API SH spec allowed phosphorus of 1200 ppm. The current API SN spec only allows 800 ppm.

If you want a high ZDDP oil, you need to get a High Mileage oil (Mobil 1's High Mileage 5w03 has zinc 1100 ppm and phosphorus 1000 ppm), or some specialized offering such as this:
AMSOIL Z-ROD 10w30 Synthetic Motor Oil (Product Code ZRTQT)
(zinc – 1440 ppm, phosphorus 1320 ppm)

Nathan Plemons

I use Mobil 1 10w30 in everything I own. On my flat tappet engines I use a ZDDP additive.

The idea that "if it's so good why didn't GM use it when it was available" is really absurd. IMHO Michelin is superior in every way to Goodyear, but the car was shipped with Goodyear tires. It doesn't mean there wasn't anything better, it means that the car was made by a corporation and corporations have bean counters along with corruption and pocket liners, as well as a generally annoying attitude of if it ain't broke don't fix it.

FWIW, in 1992 GM switched to synthetic for the Corvette but did NOT specify that the synthetic had to be Mobil 1 brand, only that it meet some certain GM specification (now it may well be that Mobil 1 was the only oil to meet the specification at the time, I was 11 so I really don't know). Only in 93 did they actually put the Mobil 1 logo on it.

MOST Synthetic oil has better lubrication, temperature stability, and flow characteristics than MOST conventional oils. This is a fact that doesn't need to be argued. Do you NEED to run it in your car? Nope, do you WANT to run it in your car? Only you can answer that. Will it make your car leak oil if you switch, MAYBE, maybe not, one way to know for sure.

Cavi

look, by all means use what you want. In most of my cars and motorcycles I use Rotella T, either the simi syn. or the full syn, depending on the vehicle. In my vette i am using mobil 1 5/30. If for no other reasons than two, it is what chevy reccomended, and second, the syn oil is said to last up to 10000 miles without changing. Now, I do change my oil every 3000 miles but it is nice to know that if needed I could go to 5000 or even slightly more and not do any harm. Also, at this point it is crazy but prices of normal oil are really not much lower than synthetic oil. they used to be but not anymore...

5abivt

Castrol motorsport 10w60. $17/qt and it sucks that I need 9.2 qts

Cavi

Rotella T syn is like 22, mobil1 is 26 at wally world. Change your oil evey 5000 miles and in 3 oil changes you be money ahead of the game....
15000 miles = 3 changes at 5000 mi or 5 changes at 3000 mi.
Rotella T 22 per 5qt jug =66 for the 3 changes
Mobile 1 26 per 5qt jug = 78
Yours 17 per 5qt jug = 85 for 5 changes