Conventional oil in c4 LT1
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
Racer
Joined: Mar 2016
Posts: 344
Likes: 65
From: Ontario, Canada
Am I supposed to use synthetic in my 90 L98? Obviously not Lt1. Hell it's just an old small block Chevy. Was synthetic even used much 30 years ago?
Last edited by Beater12; May 16, 2021 at 10:10 PM.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
The oil life montior would be skewed so the oil would be totally worn out before change oil light comes on. The calculation is based on Mobil1s rate of breakdown. Tracking would be a bad idea largely because increased cooling temps. If car is only used seasonally and oil changed at 3-4k it would probably be ok. The LT1 got Mobil1 because the oil cooler was removed.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Pro
Joined: Mar 2007
Posts: 596
Likes: 355
From: Mt Prospect IL
2025 C4 of the Year Finalist - Unmodified
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
GM went to full synthetic oil (Mobil 1 was the factory fill) for the LT1 when they discontinued the oil coolers. The full synthetic has better resistance to thermal breakdown.
I would want full synthetic in my cars.
It is even cheaper than that. There is currently a rebate from Mobil 1 that brings it under $15 for a 5 quart jug.
https://acbincentives.com/mobil1/terms.asp
Good luck.
I would want full synthetic in my cars.
Mobil 1 at Walmart under $25 for 5 qts. https://www.walmart.com/ip/Mobil-1-E...ipack_quantity
https://acbincentives.com/mobil1/terms.asp
Good luck.
Burning Brakes
Joined: Sep 2016
Posts: 1,133
Likes: 319
From: Ohio
Racer
Joined: Jul 2012
Posts: 332
Likes: 74
From: MUSKOGEE COUNTY OKLAHOMA
Thread Starter
Cruising
Joined: Mar 2021
Posts: 11
Likes: 0
I'm going with a high mileage full synthetic I was just curious what everyone thought I'm sure the synthetic is better but at the end of the day it is a 350 small block they've been running for year and year I highly doubt conventional would destroy the engines
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
Burning Brakes
Joined: Sep 2016
Posts: 1,133
Likes: 319
From: Ohio
Non synthetic oil today is better than the synthetic these engines were designed to run on from 30 years ago.
I assure you the bearings will be fine. Don't be such a stickler.
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
You are probably right. I would be beside myself in worry if I accidentally put conventional in my car. 🤷🏽♂️
Le Mans Master
Joined: Aug 2017
Posts: 6,944
Likes: 1,490
From: New Jersey
Cruising
Joined: Mar 2021
Posts: 11
Likes: 3
From: Nashua, NH
The question is why in the first place would you ever run conventional? Saving maybe 10$ ever 3-5k miles? I'm really struggling to find the logic behind this, synthetic is dirt cheap and as far as consumables on a car go, synthetic is total noise.
Melting Slicks
Joined: May 2013
Posts: 2,692
Likes: 349
From: Sacramento California
The way you drive the car does have an impact on the oil, but with synthetic oil prices being so affordable, I can't imagine why anyone would run conventional in an engine spec'd for synthetic. Having said that, I believe the reason GM went to synthetic with the LT1 is because they removed the oil cooler at the same time and synthetic oil holds up to higher temperatures better. So you could run conventional oil *if you had to* but you would want to change it more often, which makes the whole idea penny wise and pound foolish. You can get Mobil 1 for $14 a jug after rebate, 2 per household: Mobil 1 Rebate 2021
You're welcome.
You're welcome.
Race Director
Joined: Oct 2000
Posts: 14,064
Likes: 1,166
From: N. Alabama
The only engine I ever blew up running conventional oil was back in the seventies. It was sludged up and had low oil pressure. Tear down revealed a caked up mess. Quaker State. 
I run only synthetics, mostly amsoil. As was stated above, if using conventional you need to change more often which is negating any cost advantage.
I run only synthetics, mostly amsoil. As was stated above, if using conventional you need to change more often which is negating any cost advantage.