Backstory on an ultra low mile 2009 I should have in a couple weeks if nothing goes wrong (have to follow the link chain back to my first intro thread from last year for the full story): https://www.rx8club.com/new-member-f...-world-271794/

Cross linking here because I seek other opinions on premixing the S2. I've already ordered the stuff to do so but am I just wasting my time with it? Should I go lower than a quarter ounce per gallon?

Also welcome any info on DIY compression testing since the only Mazda dealer in my town charges $185 and doesn't even use the proper tool.

 

Don't overthink the premixing. You will never know what effect it had on your engine life so approach it as whether you can justify the expense even if it did nothing. Idemitsu is expensive, you can find cheaper FD-rated alternatives like Lucas. In small ratios (150-200:1) there aren't any side effects. If you're looking for studies on whether premixing helps, there aren't any with any significance.

If you're going to race, different story. Still no studies but you need to oil and cool the side seals and the stock system doesn't do that.

 

Thanks. Reckon since I've already spent the money I'll go forward at a quarter ounce per gallon for my peace of mind even if it might just be a placebo.

 

if this car is still at 7000 miles. Or even 10,000 miles, I am quite sure you dont need to worry about compression. Just drive the car and red line it. Clean those idle seals !!. As far as premix, not necessary. Drive it. Redline it. Proper warm ups and cool downs and good gas.

 

You can use a normal compression tester with the valve stem removed and film it in slow motion if you want pretty close results for very cheap. Otherwise wait until the car is nice and warm and try starting it up. If it starts quick while hot compression is pretty good