Engine Oil Type

[charlesorosz]

Hey guys, looking to replace the oil in my new project car. Engine is from 1981, but the corvette is a 75. The previous owner never told me what kind of oil he put in, nor the viscosity and if it was synthetic or not. What do you guys recommend? Thanks!

 

[charlesorosz]

Forgot to add: it’s a small block 350 with edelbrock carb, fuel pump and intake.

 

[grumpyfellow]

I’m a mobile 1 synthetic fan!! Great oil

 

[gdh]

Another Mobil1 user. What condition is the engine? Have you done a leak down test etc. If it is high mileage a good regular oil would suffice whether it be a 30, 40 or 50wt will depend on ring wear. More info on the engine would be helpful.

 

[Fred J]

I use Castrol 40wt because of the high heat. (454)

 

[Black 03 Z06]

10 W 30 or 10 W 40 and it takes almost 5 litres of oil unless the pan has been changed. Buy any good quality oil and filter.

As above posters have mentioned more info needed on the engine but I suspect you would be alright with this oil.

 

[AxeZ06]

More oil information than you'll ever need:

Passenger Car Motor Oil (PCMO) - Gasoline Vehicles - Bob Is The Oil Guy

Bob is the Oil Guy is the internet's number one motor oil site. Joing the discussion as our knowledge base expands to help you with your motor oil needs.

www.bobistheoilguy.com

 

[V8!]

When I had my C3 I was running 5W30 and it ran hot, once I put synthetic in it, it did run about 10 degrees cooler so there is a difference. Mind you that was about 15 years ago.

 

[75roadster]

I have always run conventional 10W40 oil in my '75 and added a ZDDP additive. The need for a ZDDP additive or the use of a high zinc content oil like Shell RotellaT 15-40 pertains to engines with flat tappet camshafts. If your engine has a flat tappet camshaft and is stock there's no need for the zinc additive (it won't do any harm so if it makes you feel better go ahead and add it anyway) but if it has been modified with a performance camshaft the zinc additive/high zinc content oil should be used as the pressure on the cam lobe/lifter interface will be significantly greater than stock. There used to be an issue with engine oil leaks given the low viscosity of synthetic oils but I believe that has long since been addressed. Hope this helps.

 

[72ray]

Temperatures were you live matter as well remember and catalytic converters (if you have one) don’t tolerate zinc additives that are required for flat tappet engines.

 

[72ray]

When I had my C3 I was running 5W30 and it ran hot, once I put synthetic in it, it did run about 10 degrees cooler so there is a difference. Mind you that was about 15 years ago.

That’s surprising if you didn’t change anything else as Synthetic oils aren’t generally known to be good at carrying heat away as far as I’ve been told.

 

[12cents]

I noticed it with my old Camaro years ago when I switched to synthetic that the operating temps dropped and tended to stay cooler. Funny enough, same thing in my truck.

 

[72ray]

I’m guessing improved lubrication leads to reduced friction resulting in reduced heat production rather than the benefit of any ‘coolant’ like effect of circulating oil. Big assumption on my behalf though!

 

[V8!]

That’s surprising if you didn’t change anything else as Synthetic oils aren’t generally known to be good at carrying heat away as far as I’ve been told.

Yup, I even went back to conventional for a test to make sure it wasn't all in my head, and the temps went back up. Needless to say I only ran synthetic after that.

 

[Sergio79]

I run on 10w30. I drive about only 2000 km per year but I dump the oil every spring when I get the car out of winter storage. With synthetic, would I need to dump it every year also ?

 

[Rruuff Day]

You should get lots of opinions on this question. Petroleum-based oils break down from heat and pressure. The make-up of the oil changes and it becomes contaminated over time.

Synthetic motor oils have a higher tolerance to heat and time.

 

[dannyboy]

I run on 10w30. I drive about only 2000 km per year but I dump the oil every spring when I get the car out of winter storage. With synthetic, would I need to dump it every year also ?

After only driving 5,000 kms in my Vette last summer, I made the yearly oil change but recycled the slightly used synthetic into my daily driver on its next oil change.
Then I drove it for the remaining 10,000 kms of life in the oil.

 

[ddgermann]

I run on 10w30. I drive about only 2000 km per year but I dump the oil every spring when I get the car out of winter storage. With synthetic, would I need to dump it every year also ?

Yes definitely a loaded question on here. But I would not have any anxiety about doing exactly the same as you. Many will discuss acids in the oil etc left in over winter but at 2000 touring km a year, I don't think its a big deal. Switching to synthetic is never a bad thing but likely a waste of money for you as well. The yearly conventional oil change has been working good for you so far so why change your routine now.

 

[Sergio79]

Thank you for the comments. I will keep the same recipe for now.

 

[Tristan69]

I would say it would depend on if you run flat tappet or roller tappet camshaft. Flat needs Zinc so in Canada Joe Gibbs is your best bet. There are others but that’s what my baby likes. If roller then what others say is good. Sorry no picture of my cam