CO_SKI_MANIAC

alright, got a question about fuel and whether lead additive should be used in the orignal 200-S6 or will lowest octane of unleaded work fine. i have a buddy that argues the unleaded can be used. I heard you can get a ping if you dont use additive. thoughts? thanks in advance.

69mach1377

What is the compression ratio?

Soaring

This has been discussed at length, and it really all boils down to how much lead build-up you have on your valve seats. They were originally softer than modern valve seats, so needed leaded fuel to protect them. Personally, I use a lead additive, but many guys don't and get by with it. If your compression ratio is high, then you might want to consider using an additive. I use Redline brand, but there are many on the market that will fill the bill. Also, if your engine has been rebuilt, then the harder valve seats may have been added, in which case you can get by with regular unleaded fuel. Mine has not, so I not only use an additive, I burn premium fuel in my 289. Bottom line is that adding a few ounces of lead additive certainly won't hurt your engine, and it could help it, so why not use it?

Scott H.

You should not need the lead substitute with the I6, unless you have cut the seats since we went to unleaded gas and you use the engine under extreme conditions. Constant drag/road racing, or towing heavy trailers through the hills. That kind of extreme.

I run unleaded premium (at least 91 Octane) and have bumped my timing accordingly to help with the off idle hesitation that the 6 cylinder has. Basically I'm hiding the poor engineering design of the intake manifold. It works well. It is the only reason I run premium. If I had an automatic, I'd run regular, as it's not such a drivability issue with the automatic.

Compression ratio on a stock 200 6 cylinder is 9.5:1. If you are not worried about (or do not have an off idle hesitation) the car will operate fine on 87 Octane regular. You may need to reset the timing, if it has been adjusted to run on higher octane fuel.

I'm not a fan of lead based additives, but that is more of a personal choice based on my education, and personal experience.

Do what you feel is best.