Conventional oil in c4 LT1
Burning Brakes
Joined: Sep 2003
Posts: 866
Likes: 22
From: Savannah GA
Doesn't matter as much as the zinc content in the oil. The lack of zinc manifests itself in distributor gear wear, among other places. Cheap oil usually has problems maintaining viscosity over longer periods of time, which shows especially in harder run engines in bearing wear. Meaning...
Whatever you decide to run, run a good quality oil...making sure to keep the zinc levels up as well.
It will run fine on conventional. Just make sure it's good stuff and you change it often.
...that being said, it's generally not cost effective by the time you factor in the increased oil change frequency to not run something like Mobil 1. I usually use a conventional for break in, then switch to synthetic afterwards.
Whatever you decide to run, run a good quality oil...making sure to keep the zinc levels up as well.
It will run fine on conventional. Just make sure it's good stuff and you change it often.
...that being said, it's generally not cost effective by the time you factor in the increased oil change frequency to not run something like Mobil 1. I usually use a conventional for break in, then switch to synthetic afterwards.
Last edited by dhirocz; May 17, 2021 at 02:24 PM.
Oil Producer
Joined: Apr 2014
Posts: 9,387
Likes: 2,749
This. You need to understand the pros and cons of what synthetic is even doing for you before you can answer this question and blindly putting a $60 jug of oil in vs a $10 jug (those are the price ranges where I live in Canada).
Driving conservatively....you will not even come CLOSE to the upper end of the temperature limits of conventional oil. I run it on the track all the time.
Most people have no idea the Marketing arrangements that were held between Mobil1 and Corvette at the time and what they entailed. It has nothing whatsoever to do with bearing clearances.
That said, monitor your oil and give the oil changes it needs! Whatever you decide to put in it.
Oil Producer
Joined: Apr 2014
Posts: 9,387
Likes: 2,749
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.
If I could get this full synthetic at these prices, I would without question.
Melting Slicks
Joined: May 2013
Posts: 2,692
Likes: 349
From: Sacramento California
I thought Zinc was a big concern for the older solid-lifter designs...? The LT1 has roller lifters. Yes there is a need for zinc as a failsafe barrier protection but not as much as the older engines needed.
Also the optispark is gear driven off the camshaft but I can't say that the optispark has a distributor gear in the conventional sense. In other words, it doesn't have one of these:
Also the optispark is gear driven off the camshaft but I can't say that the optispark has a distributor gear in the conventional sense. In other words, it doesn't have one of these:
Safety Car
Joined: Sep 2001
Posts: 4,162
Likes: 555
From: Glenbeulah Wi
Thread Starter
Cruising
Joined: Mar 2021
Posts: 11
Likes: 0
I honestly don't think it's that deep myself obviously I think going full synthetic is the best option overall for cost effectiveness and protection but IF you for some reason wanted to run conventional just change it every 3k to prevent sludge seems pointless to do so but whatever floats your boat it's not a life and death thing
Burning Brakes
Joined: Sep 2003
Posts: 866
Likes: 22
From: Savannah GA
I thought Zinc was a big concern for the older solid-lifter designs...? The LT1 has roller lifters. Yes there is a need for zinc as a failsafe barrier protection but not as much as the older engines needed.
Also the optispark is gear driven off the camshaft but I can't say that the optispark has a distributor gear in the conventional sense. In other words, it doesn't have one of these:
Also the optispark is gear driven off the camshaft but I can't say that the optispark has a distributor gear in the conventional sense. In other words, it doesn't have one of these:
Ever see that fail? Usually costs you an engine. You need to understand the EPA has pulled zinc out of oil for years because it was supposedly bad for the environment, but in reality it just made making oil cheaper, less additives required. All it did was reduce the effective service life in engines like the LT1. It doesn't affect them as much as a flat tappet engine, but still poses problems. The EPA wants to try to force you out of your older car and into a newer one. Keeps the economy going.
Racer
Joined: Mar 2016
Posts: 344
Likes: 65
From: Ontario, Canada
My understanding is that zinc is only available as an additive. Apparently it was available in heavy duty diesel oil but that is not longer the case. My old Fiat used to require it but will an L98 really require it?
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Drifting
Joined: Aug 2019
Posts: 1,341
Likes: 225
Safety Car
Joined: Jan 2004
Posts: 4,549
Likes: 343
From: Glastonbury CT
If you use Mobil one it can be good for twenty thousand miles. Just change filter every six months . Look for the container with the 20,000 oil change listed. It is new to market! Walmart has it under$25.00
Le Mans Master
Joined: Dec 2004
Posts: 5,488
Likes: 1,352
It will run with conventional oil and 87 octane gas too and straight water instead of antifreeze, can run without a thermostat too 
Pretty sure it will run with a couple plug wires off. Won’t run right but it will run.
Pretty sure it will run with a couple plug wires off. Won’t run right but it will run. Last edited by JD'S WHITE 93; May 17, 2021 at 06:52 PM.
Racer
Joined: Feb 2004
Posts: 428
Likes: 87
From: Rockwall TX
zinc /ZDDP is needed in the older flat tappet engines to prevent cam lobes from getting wiped, needed less so with roller lifters. EPA cut the amount from 1200ppm to 800 and less to reduce harm to catalytic converters. CJ-4 was the last API rating for 1200 iirc
Burning Brakes
Joined: Sep 2016
Posts: 1,133
Likes: 319
From: Ohio
Burning Brakes
Joined: Jun 2016
Posts: 761
Likes: 66
From: Fitzwilliam New Hampshire
I've been using mobil one high mileage 10W40 with 110000 miles in my 94 lt1 and have very good oil pressure even hot idle. Never gets run in cold temps, like below 50 degrees out side.
Drifting
Joined: Apr 2014
Posts: 1,699
Likes: 231
From: Hawthorne CA
my engine builder specified that I use 10w40 in the engine he built me. He was very specific and insisted that I use synthetic 10w40. I would think he was this specific for a reason?
Instructor
Joined: Mar 2021
Posts: 169
Likes: 25
Why not olive oil? My Father in law works dor Bertolis and can get unlimited product. I want to use Olive oil so I can drive conservatively to Starbucks every day...
Serious note, doesn't synthetic also free up horsepower and therefore better gas mileage? I know I can tell a difference just in my 74hp Prius. It was having typical Prius oil burning problems (4.75 quarts lost in 4000 miles, no joke) with cheap Walmart oil, I drive 1000 miles a week. I read a post, someone reversed the oil burning with Royal Purple and Redline. So I gave it a shot. Wouldn't you know, after a topping off with just 1 bottle it was smoother and It had better acceleration. After a month of adding, its stayed full. I'm a believer now. As for mileage, Prius also have shoddy instrument gage clusters that burn out, so I can't comment on gas mileage but the same guys who switched gained 3 to 5mpg. Half that for V8 motor, is still worth it.
Use cheap oil if you want, it won't hurt none, but you aren't saving money for Starbucks. 2nd thought, get your coffee at home save hundreds.
Serious note, doesn't synthetic also free up horsepower and therefore better gas mileage? I know I can tell a difference just in my 74hp Prius. It was having typical Prius oil burning problems (4.75 quarts lost in 4000 miles, no joke) with cheap Walmart oil, I drive 1000 miles a week. I read a post, someone reversed the oil burning with Royal Purple and Redline. So I gave it a shot. Wouldn't you know, after a topping off with just 1 bottle it was smoother and It had better acceleration. After a month of adding, its stayed full. I'm a believer now. As for mileage, Prius also have shoddy instrument gage clusters that burn out, so I can't comment on gas mileage but the same guys who switched gained 3 to 5mpg. Half that for V8 motor, is still worth it.
Use cheap oil if you want, it won't hurt none, but you aren't saving money for Starbucks. 2nd thought, get your coffee at home save hundreds.
Team Owner
Joined: Jul 2004
Posts: 28,501
Likes: 3,302
From: Hartford WI
Why not olive oil? My Father in law works dor Bertolis and can get unlimited product. I want to use Olive oil so I can drive conservatively to Starbucks every day...
Serious note, doesn't synthetic also free up horsepower and therefore better gas mileage? I know I can tell a difference just in my 74hp Prius. It was having typical Prius oil burning problems (4.75 quarts lost in 4000 miles, no joke) with cheap Walmart oil, I drive 1000 miles a week. I read a post, someone reversed the oil burning with Royal Purple and Redline. So I gave it a shot. Wouldn't you know, after a topping off with just 1 bottle it was smoother and It had better acceleration. After a month of adding, its stayed full. I'm a believer now. As for mileage, Prius also have shoddy instrument gage clusters that burn out, so I can't comment on gas mileage but the same guys who switched gained 3 to 5mpg. Half that for V8 motor, is still worth it.
Use cheap oil if you want, it won't hurt none, but you aren't saving money for Starbucks. 2nd thought, get your coffee at home save hundreds.
Serious note, doesn't synthetic also free up horsepower and therefore better gas mileage? I know I can tell a difference just in my 74hp Prius. It was having typical Prius oil burning problems (4.75 quarts lost in 4000 miles, no joke) with cheap Walmart oil, I drive 1000 miles a week. I read a post, someone reversed the oil burning with Royal Purple and Redline. So I gave it a shot. Wouldn't you know, after a topping off with just 1 bottle it was smoother and It had better acceleration. After a month of adding, its stayed full. I'm a believer now. As for mileage, Prius also have shoddy instrument gage clusters that burn out, so I can't comment on gas mileage but the same guys who switched gained 3 to 5mpg. Half that for V8 motor, is still worth it.
Use cheap oil if you want, it won't hurt none, but you aren't saving money for Starbucks. 2nd thought, get your coffee at home save hundreds.
Racer
Joined: Aug 2016
Posts: 253
Likes: 59
From: North TX
Shell Rotella T6 full synthetic 5w40 is my drink of choice.
In my opinion - If you want to find out how to keep things alive, look at diesel technology and how they are maintained. In addition to the old vette I beat on and the countless high HP/RPM streetbikes I've had, I've owned 6 diesel powerstrokes ranging in mileage from 25k to 650k worked HARD. Newer LS stuff, my lawnmowers, wife's ecoboost - All of them get the same oil. Everything I own gets that stuff.
In my opinion - If you want to find out how to keep things alive, look at diesel technology and how they are maintained. In addition to the old vette I beat on and the countless high HP/RPM streetbikes I've had, I've owned 6 diesel powerstrokes ranging in mileage from 25k to 650k worked HARD. Newer LS stuff, my lawnmowers, wife's ecoboost - All of them get the same oil. Everything I own gets that stuff.
Heel & Toe
Joined: May 2021
Posts: 17
Likes: 2
From: MN
I would stay away from the conventional stuff with todays options. Synthetic=more consistent viscosity, shear stability, typically more advanced additives. Conventional will work fine but in a much narrower set of parameters. Synthetic allows for performance at more extreme conditions. Things like ZDDP and phosphorus vary between synthetics and conventional. As an Amsoil dealer, I will be running ZROD in my 396 for the extra zinc. I run HD Marine in my Cummins 12V after I tired of the Shell T6 thinning down. Of course I am biased towards Amsoil as I get it for wholesale. Tough to beat at those prices.