I have an 85 GSL-SE with 123k on it that I have owned for just over 8 years. I run Castrol GTX 10W30 most of the time. I have some Castrol GTX 5W30 that I bought for my Maxima, but have decided to switch it to synthetic and can return the oil. I have enough 10W30 for my next oil change, but am considering switching the other 5 litres for 20W50 for the RX7 for next spring/summer/fall usage.

I've never run 20W50 in the RX7. Is there any noticeable difference in fuel economy with 20W50, relative to 10W30? I take it that the oil consumption is lower with 20W50. The 10W30 is presently being consumed at about 1 litre per 1,600 miles or so.

Thanks

 

Oil consumption should be no lower with 20W50. IMO, its not worth the change unless your car regularily sees 100*F or more. Regular 10W30 is best. But, if you do switch and see less oil consumption, I would be worried. The rotary consumes oil by design at about the rate you said. Thats why I say I'd be worried.

 

Thanks. I live just outside Vancouver and we don't even get to 90 Fahrenheit here. I guess I'll just stick with the 10W30.

I guess I should know more about oil for these engines than I do, lol! I have owned two 79 RX7s, a 1974 RX4 and a 1970 R100 that I blew the engine out of at about 40K, but got a new one for free from Mazda.