Originally Posted by Wisconsin S2k,Apr 27 2005, 02:48 PM

Let me clear up a few things. And yes this is scientific fact. If you live in the UTH forum you'd know.

From the factory, the engine oil contains a high amount of soluble molybdenum sulfide. When an engine is put together, the internals such as piston walls, valves, etc, all look smooth, but under a microscope, have tiny ridges and "mountain" surfaces. This causes the engine to run hotter during breakin period. The moly helps dissipate that heat. Furthermore the moly assists in honing down those surfaces to make them smoother.

1000 miles is NOT long enough for proper breakin. Honda says don't change factory oil until 7500 and that's the reason. The moly needs to help the engine dissipate that heat so it doesn't run so hot, and so those surfaces smooth out. Wait 7500 to change the factory oil. Changing at 1000 miles or too soon in any way, will likely reduce the life of your engine. Since things won't smooth out and seal properly, for example, you'll burn more oil, run hotter, and could over time cause something as bad as a scored cylinder sooner than would normally happen if the car was allowed to break in with the moly oil properly.

Also DO NOT go to synthetic BEFORE a good 7500-10,000 miles or so. The reason for this is our FRM (fiber reinforced metallic) cylinder walls!! If memory serves me, the reason is synthetic oils may not properly coat and assist the breakin of the FRM walls, and the FRM cylinder walls will take some extra time to break in and smooth out/seal properly. Again, no immediate damage, but likely reduced engine life. There was never anything official from honda on this, but that's because it was assumed people would wait 7500 to change the first oil as the manual said. A model of the older preludes had FRM cylinder walls, and there was actually a TSB for that model stating not to use synthetic too soon for that exact reason.

Originally Posted by Mikeycharged,Apr 28 2005, 11:20 PM

This has finally cleared things up for me. I have been reading the FAQ's on the oils and still didn't have a clear answer.

I was so use to changing my oil every 3K and was unsure of leaving the factory fill until 7.5K. I just picked up my 05 Rio and want to take the best care of it as I can.

I guess I will leave the factory fill in until 7.5K than change it out to Castrol GTX(dino). After that, change it out to Mobil1 syntec at 10K.

Is this correct?

Also, I have only been up to 4.5K on the tach. When is the best time to hit 8K?

I was thinking about 1K miles and I would be good but since it seems like you know a little more I would like to hear what you think.

I always waited to about 600 miles on my other Hondas until I ripped on them but I wanted to wait till 1K for the S. Is 1K miles good enough?

Thanks in advance.

Mike

Originally Posted by Wisconsin S2k,May 1 2005, 07:05 PM

honestly, when you let your car rip is all up to you. FWIW i started vtec'ing mine at 300 miles, but some have said they waited 600 miles. it's really kinda up in the air.

Originally Posted by s2000amuse,Apr 27 2005, 03:23 PM

Synthetic bad ?