Originally Posted By: ekpolk
Originally Posted By: Solo2driver
My father-in-law has an '07 IS250 and the manual specifically states that the use of synthetic oil is not recommended.
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Where are you getting that from??? My wife drives an 07 Avalon, which has the 3.5L version of the xGR V-6 (the IS-250 has a lower displacement version of the same GR series engines), and the manual for the same-year Avalon says nothing about discouraging the use of synthetic oil. Zero. Seeing your original comment, quoted above, I logged into Techinfo.Toyota.com, and checked all the on-line service pubs for the 07 IS-250, and there's absolutely NOTHING in the official pubs about not using synthetic oil. Please tell us precisely where that info is coming from. It may be good, and if it is, I need to tell the TIS folks to get their on-line data squared away. On the other hand, I've owned a number of recent model Toyotas, and I read all of their manuals (including that of my wife's Avalon, again same year, different version of the same engine), and I've seen no mention at all of such a restriction. If your info is correct, we need to see exactly where it fits.
I'll grab the glovebox manual from him next time I am in Austin....when he picked up the car, we read through it, and it was of fairly huge note in my mind that there was a line about recommending against synthetic oils. When he had his old '97 Accord V6, he picked up a few mpg and longer drains when he did road trips (kept detailed logs for work, as he claimed it as a company car), and we were both disappointed when we read it, and he has just been going to the dealer and getting dino to maintain the warranty.
If I'm wrong that would be awesome, but it sticks out in my mind that we both read it in the manual and were disappointed. Hopefully there was a reprint or addendum allowing for synthetics.