MisterC

I'm thinking of selling my C6 and getting an older classic Vette. I'm curious about burning unleaded in an engine that was designed for leaded gas. What's the consequence? Is an additive of some sort required?

Thanks for your responses.

Mike Ward

No additives required- straight pump gas is just fine.

Easy Mike

Food For Thought: older Corvettes are completely different animals when compared to your C6. You could end up disappointed.

54greg

I have both. One is both a tool and a toy the other is just a toy. Be aware

TheSkunkWorks

Most any early C3 engine is going to have been rebuilt by now, and should already have hardened valve seats installed during the valve job which allow use of unleaded gas without concern of valve seat recession. That said, there are lead replacement additives for any engine that hasn't been brought up to date.

If you're strictly looking for style, IMHO the C3 is it. That said, I agree you may well be dissappointed with the performance of a C3, coming from a C6, but I wouldn't let that aspect stop you, particularly if modding isn't out of the question. There are sharks in these waters with plenty of power that can pull a G.

Mike Ward

No Corvette ever required lead to avoid valve seat recession- that's an old myth that won't die. I'd guess that very few of them had hardened valve seats added too. Not required.

briankeery

You may have spoiled yourself driving that beauty......good luck though, if you decide to make the swap.....you can probably buy a lot of C3 for the replacement value of that one.

Vette5.5

If not driving the car much, really wouldn't worry about it. You can always put in a can of lead substitute if wanting to. As mentioned, if the heads are, or to be reworked, hardened valve seats are usually installed at this time. Gotta agree with the C6 comments, as have a C6 ZO6, and this thing's a keeper.

MisterC

You guy's have really been helpful, thanks a lot. Don't drive the C6 much, either. I was thinking os something maybe more classic, like myself. (LOL)

CQRT

Robert- I can completely understand your situation. I'd owned ten Corvettes going back to the 70's - - one of my favorites was a `73 small block coupe. Our 2005 Z51 C6 was by far the fastest and a great road car- even with the addition of a Billy Boat exhaust, it just lacked something.

I decided I needed another "oldie" and bought a `73 from a great guy that had owned her for more than 30 years and had every record and receipt (except gas) and brought her home last Fall. It's been a labor of love (and a considerable expense to rebuild so many things) but I couldn't be happier.

That's my .02 - - good luck with your decision ! (and thank you for your service to our country )

Easy Mike

I like that. Instead of being an Old Fart, I think I'll became a Classic.

MisterC

The flip side of that is that I'm a member of the 'Old Guy's Car Club of Rockwall, Texas'.

Mike Ward

Be aware that the 'lead substitutes' contain nothing to protect the valve seats, they're merely octane boosters.

TheSkunkWorks

Red Line Lead Substitute "prevents valve seat damage in engines designed for leaded gasoline".

http://www.redlineoil.com/product.aspx?pid=78&pcid=12

HamadUP

BEWARE!, these lead additives are EXTREMELY poisonous!, handle them with extreme care, that nasty stuff can even be absorbed by your skin.

I strongly recommend not to use these additives as you won't need them anyway, the valve seat damage is caused by full loading an engine for a long period of times, such as towing, engines used in RVs ... etc, but a Corvette engine will not be harmed even if it hasn't hardened seats.

Mike Ward

Exactly- a Corvette engine never runs hard enough for long enough to induce the microwelding issue. This is a different story if towing a trailer up a mountainside or an RV, marine use etc. etc.

Paul L

A 1979 L-82 (350/225), a 1967 327/300, and a 1974 L-48 (350/195) for many thousands of miles without additives.

KenSny

I don't run additives in my 75 L-82 modified that is still around 9:1 comp.

However, I cannot run anything with ethanol or regular 87 octane.

Sometimes even 89 octane is a problem, depends on the brand. I never have a problem with 93 octane and since I don't put more than 1000 miles on it a year, the cost difference is not a factor to me.

commander_47

Some engines are more prone to damage from unleaded gas. For example, Harley flatheads will quickly fry the valves if you do not put in hardened guides and valves.

The fact of the matter is, any car that has had a valve job in the last 20 years is probably capable of burning unleaded fuel with no problem. Since the new parts will tolerate it. I don't think there are many C-3 cars out there that are actually driven that haven't had some head work.

By the same token, older, unrestored engines will not do well with modern oil. All of the detergents and additives will wreak havoc on an older engine designed to use straight 30 weight. Again, if your engine has been worked on with new seals, bearings, etc, then it's probably ok.

Any gas with ethanol is worse than the unleaded gas by itself in an older engine.

The additives you need to replace, probably more than lead, are sodium and potassium.

I have, and have had, many older cars/motorcycles and have found that a shot glass or two of Marvel Mystery Oil in the gas tank works wonders for the oldies.