Originally Posted By: HTSS_TR
If you are changing from dino to synthetic for the first time, you should do a fairly short OCI (oil change interval) at around 6-7k miles, then extend to 8-10k miles or 1 year. Purolator Classic filter is okay for any OCI up to 8-10k miles if your engine is fairly clean.
I respectfully disagree with this "blanket" assertion (but it is due to a blanket question). These are all different engines and have different characteristics. QSUD is a great oil (no question) but this question is very hard to answer.
To make it simple and SAFER, I would not do more than 6-7k 6mo. OCI's on these vehicles.
If you give some specifics on the type of driving you do in each car and the Highway/city ratio it is a little easier.
If you really care do UOA's at 6k, if not don't extend too much more than what you usually do. You got a bargain anyway, the stuff isn't a miracle oil.