jmanlang

I would suggest to stick with premium unleaded. You have a high performance car. I have put regular unleaded for a couple of months and noticed a drop off in acceleration. Went back to super unleaded. My GS 400 is back was back in business runnng like a high performance car.

I just replaced my battery and never did any computer resetting. Your GS should be fine.

I also have a 98 GS400. I have tried putting a plus unleaded from time to time, and it has caused no harm. However, I noticed that my gas mileage per galloon have drop off a bit. I would recommend to sticking to premium unleaded. Pings only occurs on heavier loads. However, if I was you I would not completely switch to regular or plus unleaded. There has been quite a few research on this forum in regards to using a regular unleaded gasoline. Just do a search and you will see more comments about it. Good luck and enjoy your GS400!!

GS300 is a V6 and GS400 is a V8 engine. Therefore, V6 will get you a better gas mileage. However, I would go with the GS400 because it provides more power (300hp vs 225), and probably has a better ride handling than a GS300. In addition, GS400 is more comparable to a BMW 540 series, but the GS400 is probably priced at a 3 series. Yes, they do take synthetic oil. Good luck.