Synthetic oil and Decarb

Just this morning I performed a decarb on my 97 Mariner 125 and it sure cleaned up good. I had inspected the cyl's with a bore light and they had a pretty good coating of carbon on the piston tops. I used one can of Seafoam mixed with a gallon of gas and ran it all thru. After letting it sit I fired it up and what a cloud of smoke! I inspected the cyl's after and the piston tops look like new. I also switched to pennzoil full synthetic and noticed a smoother idle and almost no smoke at all on start-up or idle. I was somewhat shocked that after the decarb and oil change, my top speed increased by 3 mph. Just to be clear on this, I always have been very skeptical of performance gains from either of these two changes, but both showed signs of better performance in the motor, and I am now a believer in synthetic!!

Re: Synthetic oil and Decarb

just curious, did you use the engine with regular oil after the decarb and then see additional benefits by going to synthetic?<br /><br />From how you wrote it, it's hard to tell what improvements would be due to the decarb versus the change to synthetic (sounds like you did both things at the same time).<br /><br />Brent

Re: Synthetic oil and Decarb

You're right. I did both at the same time so I can't scientifically pinpoint the origin of gains, but my gut feeling is that the decarb provided the bulk of the top end increase. The new lack of smoke has to be a result of the synthetic, as well as helping to smooth the idle. This alone makes it worth the money to me. To be honest I really don't care where the extra top end came from, I'm just thrilled it's there!!!