I am wondering if 5W20 could be used in cars that use 5W30 as standard oil. I live in Vancouver BC, so the temperature is not hot. The hottest day in the year is only 79 degress F. Do you think I can use it?

PS. I want answer quick, but people on the other forums are sleeping or something.

 

Your engine was engineered with a specific oil type to meet specific tolerances. I would stick with the specs.

Is it worth ruining your engine? What will you gain, 2 mph? How long will that take to pay for a new engine, if anything occurred?

 

Even 79 degrees that would be pushing it a bit.

However, if you use 5W20 G5 lube, then the added headroom of the oil can easily work in your situation. G5's are ester-based synoils such as RedLne and some Motul.

I am going the other way - using a 5w30 G5 lube in my TL-S for reserve film strength in the bearings, rings, and cam lobes.

The G5 has better cold weather performance than even the sewing machine oil 20 weight.

 

I thought the guy who owned an RX-7 uses 5W20 in his cars. Isn't my car alot cooler than the twinturbo rotary?

thanks.