The reason I ask because I've learned from other groups and magazines talking about the Toyota recommends 5W30 for new cars due to the engine gelling and resulting in sludging problem. And 5w30 can easily reach anywhere in the engine faster than 10W30 & 10W40 and further reduce the possibility of engine gelling & sludging. My Previa owner's manual recommends 10W30 or 10W40. The manual also shows that temp. range is from 50 degre F. to less than 50 F with no limit. But, the '02 manual shows the temp. for 5W30 is from more than
100 degree F to less than 0 degree F. Why there is such discrepancy??? Anyway, I've always used
10W30 on my Previa and '90 Corolla. The Previa engine is pretty clean from the last time I checked when I opened the valve cover. I also use synthetic oil on all my Toyotas in early days. Now, I use synthetic oil for engine flushimg purpose. I heard that '94 and above Previa use 5W30. Is this true?? However, my '02 Highlander owner manual recommends to use 5W30. I have stocked both 5W30 & 10W30 oil. For convenient and good purpose, I'll like to use 5W30 for all my Toyotas. I figure if I can use it on Previa then I can use it on '90 Corolla. Any insights and suggestions are welcome and appreciated.
All the best, Matt