I have read pretty carefully the information on LC. Since you are using Redline, Amsoil, (and in my case )Mobil 1; all synthetic, i.e., group IV oils, I would say NO! In my opinion you ought to get oil analysis if you want to continue at 7500 miles (ie why are you changing SO early? problems?) Seems to me those oils are good to go to at least 15,000 mile OCI's.
I would however consider using FP in the fuel system. FP if you are willing to buy a gal is cheaper per treatment than Chevron techron even at 2.50 per treatment bottle.
Incidently, I have been doing 15,000 mile OCI's with 5w30 Mobil 1 on 5 TLC's,(INXS of 750,000 miles). I currently have two TLC's. 66,000/130,000 miles, both I6's. Both have just recently been to the dealer for the 60k/120k major scheduled maintenance intervals. (as you probably know) The upshot to both is the ASE Landcruiser specialist technician, in addition to doing comprehensive maintenance and checks, removes the valve cover gasket at both intervals and checks and adjusts the valves. On both, the valves were measured and NEITHER needed adjustment. In addition both innards were pronounced bone spotless and with original oem tool markings visible.
In addition, CA requires a 10 year smog only station and I took it 94 TLC into the rarer and more test rigorous "smog only" station, even as I felt with 116,000 miles that it needed a major tune badly. It also had something like 13,000 miles on the Mobil 1 5w30 OCI. The vehicle passed the smog only test with flying colors!!!!! I compared the test with one of the first and it was virtually identical if not a tad better!!!
So not only clean on the OUTSIDE (emissions wise) it is clean on the inside!!!
[ December 10, 2005, 08:39 PM: Message edited by: ruking77 ]