Re: Unleaded

Posted by DrewLA On 2016/6/27 10:24:47

At high engine speeds and loads, exhaust valves get hot. At high temperatures, the valves actually form micro-welds with the seats each time they close. When they open, these micro-welds are broken, displacing minuscule amounts of material and creating a rough surface which would slowly abrade the seat. Small, but over 1,000s of miles it adds up. Lead protected exhaust valve seats by forming a coating on the valve and seat, just like it coated everything else, in gunk. That microscopic coating of lead and lead oxide acted as a buffer against the micro-welding process.

However, lead use also resulted in a whole host of other issues, such as regular spark plug fouling, engine oil contamination, ring sticking, and exhaust system rust-out. The worst thing that can happen to an engine that runs unleaded is that it'll need a valve job.

In pretty much anything made before the early 50's today's 87-octane regular gasoline is more than sufficient from an octane requirement perspective. You should be aware that almost all octane-boosting additives use alcohol as their active ingredient.