May off topic, and I did search but could not find a definitive answer. I put my first crankcase of synthetic (Mobil 1) with my last oil change. Someone told me once you use synthetic, you cannot go back to regular oil.

Is that true?

 

No that's not true. You can mix the oils as well if you need a quart and have no synthetic. They are fully compatible. You can use synthetic and then go back. Why you would? I have no idea.

JET

 

Have been using ELF 5W-40 Excellium LDX with very good results

 

Before you take the above too seriously, time yourself and see if you're right. You can do a coast-down time from a given speed, measure time to coast from a given speed over a measured distance, or the time to coast from one speed to another. As a lifelong racer, I can tell you how far off I and all my friends have been when guessing at lap times, acceleration etc by the seat of our pants. I took the pole once with what I thought was the slowest run I had that season at that track.

There's just no practical way what you describe could be true, even though it may feel like it to you - you can't possibly be losing 60 horsepower to your oil. Just measure your 0-60 times before and after a change and you'll find out for sure.

 

Nope!

bill