I think one of the utilities of this web site, is at least one can chose their path with or without the data behind. Some folks after reading all there is to read, still want to do 3,5,7.5k, OCI's and in a lot of cases, despite what the oem recommends.
For me, I am clearly out of the "old" school, even though you would be hard pressed to know it, given my posts. In my humble opinion, oil(synthetic especially, as oil has been oil) and the oil additives are way better, given we no longer use leaded fuel. I used to help my father take engines apart as a boy and you probably can guess who was on the sludge cleaning detail...
At that time yes, 3,000 OCI's was pushing it!!
Not to make a long story longer, but one of the TLC's just recently (116,000 miles) was required to take a "smog only" test at the 10 year mark. This smog only test station test is specifically designed to get "old" cars off the road or render them illegal due to non compliance with smog emissions standards. They of course charge you big bucks for this wonderful opportunity. The truck had app 9,000 miles on the OCI and in my opinion, badly needed a tune up.
The truck passed with absolutely flying colors!!!!
As a point of comparison, I took out the first (biannual) smog certification. It was actually below the measurements done 8 years before.
In addition I took it into the dealer for a 120k major tune up at 125,000 miles.
( I should probably mention I do the 30k major tunes with Mobil One 15,000 mile OCIs inbetween) As part of the major tune, they take off the valve cover, etc and every 60k measure the valve clearances and adjust if necessary. It needed no adjustment for the second 60k cycle. They also made it a point to tell me the innards were SPOTLESS with factory tooling marks still visible.
However this has been SOP with a total of 5 TLC's (87,91,94,96,97) with the most noteworthy TLC having 250,000 miles when it was sold.
