My 1998 GS 400 (85,000 miles) runs great with regular 5W-30 oil and regular changes at 3,000 miles. With so many good reports on Synthetic oil , I may change to a Synthetic oil like Mobil 1 on the next oil change and keep the vehicle using a synthetic oil for the future. Has any one done this and are there any advantages besides longer change intervals. I know the cost per quart will be considerably higher.
I have a 2001 GS300 with 180,000 kms and I just switched to synthetic. I went with Castrol Syntec 0W30, which is the "German Syntec" so it is fully synthetic. Canadian Tire had on sale here for $6.56 a litre so it wasn't much more than conventional, especially if you change it yourself. The local Toyota dealership charges $90+ tax for a synthetic oil change and they use Mobil 1. I also went with the NAPA Gold filter which is made by WIX and is apparently a quality filter. Six litres of oil (it takes 5.4), $10 for the filter and $2 to dispose of the old oil and I'm done for under 60 bucks.
My GS has no leaks and doesn't burn any oil so I had no qualms about going with the 0W30. Haven't noticed any difference in performance as some people claim (not sure how they could notice any small difference it could make) and the car runs at about the same temperature as before. My main reason for the switch is I feel the synthetic will be a little better for our cold Canadian winters and should allow for better lubrication for those cold starts. I'll probably not go much longer between changes but may go to the 8000 kms "normal service" change as opposed to the 5000 km "rough service" interval that I have always went with in the past.