Premium, Regular Or What?

[ramblnman]

One place I read where the RX 400H requires premium fuel and then another site like Edmunds says regular. Which is it?

[SOMEONE ELSE'S GOT MY NAME]

One place I read where the RX 400H requires premium fuel and then another site like Edmunds says regular. Which is it?

The 400h is designed to run on either (discussed at length in many an other thread ... thus, the search tool is a wonderful thing :D ) . . . that being said, you WILL get slightly better mileage running a higher octane gas. The differenct is just enough to offset the added expense, too.

[RX400h]

I believe our manuals specify 89 octane, although I have successfully used 87 during the Winter months. Colder temps allow almost any engine to run on lower octane and by the same token, very high temps tend to allow fuel to ignite more easily. This is why I tend to run 89 octane during warmer weather. Premium is a good choice if you want to extract every last bit of power from the engine itself. It is certainly NOT necessary, however.