Originally Posted by jb78L-82

I agree with the comments above about if you change your oil at least every 3,000 miles with organic oils that any engine should be fine as long as the oil has the appropriate amounts of ZDDP. However, as for no benefit to synthetic oils, I would disagree with comments about "pretty" packaging is the only benefit to synthetic oil. It is an undisputed fact from years of research and real world testing that a conventional oil versus a synthetic oil will definitely result in more wear in any engine run for many miles, not just racing engines. Racing engines accelerate the wear curve for the engine into a much shorter time cycle and will utimately mimic the wear one would experience in 100,000 miles of normal driving into 500 miles or less of racing. Tests conducted comparing 200,000 miles on engines with conventional oil versus organic oil results in very little wear for the synthetic versus a "junk" engine of the exact type of motor using organic oil. The reason for this difference is that synthetic oils have molecules that are exactly the same size resulting in even wear protection versus conventional oils that have molecules of different sizes, superior flow characteristics at low temperature for the synthetic and at start up, and much superior high temperature protection versus a conventional oil. Synthetic oils cost more for a reason and the price difference versus a good quality oil like Shell Rotella is very small at retail outlets like Wal Mart where Shell Rotella costs about $16 for 5 quarts versus Mobil 1's 15W-50 Racing or 5w-40 Turbo Diesel which costs <$22 for 5 quarts. For a $6 difference, I would recommend the these 2 Mobil 1's for Flat Tappet engines, these two Mobil 1 weights only, not the others with less ZDDP. A friend of mine who has PHD in chemistry form the University of Chicago told me that there is absolutely no comparison between synthetics and conventional oil. Some of the above information comes from him. Hope that this helps explain the diifference between the 2 types of oil. Lastly, I still change my oil every 3,000 miles with a synthetic even though you can go longer. Check out this article for more info:http://www.carcraft.com/techarticles...oil/index.html

Originally Posted by Apocolips

I guess that I'm note as proficient as most, what is a flat tappet engine? Is a stock rebuilt 350 a flat tappet engine?

Originally Posted by jb78L-82

. Many high performance cars today including corvettes (about 15 years now are filled with Mobil1 at the factory, Porches, BMW's etc, all are factory filled with a synthetic. If its good enough for them, it's good enough for me!

Originally Posted by panic

The new Bmw M3 (V8 engine) uses an ultra thing running in oil for the first 3.000 miles, then you go to Castrol 'Edge' (former RS) 10/60.

How come ultra thin? Could that be a procedure good also for chevy V8's?

Originally Posted by machineman

Do you actually know your bearing clearances?