Which Gas Whould You Suggest For Rx300?

[NewportLori]

Due to the current price of gas, I thought it might be timely to address this issue again.

I have always used regular (87) in my 1999 2WD RX 300 and never had a problem. I use mostly Chevron, but buy from Costco whenever I can. I get what I consider to be excellent gas mileage of 19.8 MPG combined mileage and about 23 MPG on long freeway trips when I calculate it manually.

My LUV also passes smog with no problems whatsoever. If I remember correctly, lower octaine fuel causes fewer emmissions.

Are there any modifications that can be done to further increase MPG on RX 300s?

[blk_on_blk]

You guys know, there have been numerous studies that show an engine rated for regular unleaded gets no benefit from running midgrade or premium fuel: http://www.ftc.gov/bcp/conline/pubs/autos/octane.shtm and http://autos.yahoo.com/consumerreports/art...st_driving.html ...you're getting no improvement for the increased octane/cost, although you may perceive you are. If you are truly solving your detonation problem by stepping up to a higher octane, then your engine is in need of a tune up or something is malfunctioning (like your knock sensor).

As to Costco gas, well, Costco is pretty strict on all their products they sell. Their gas is good stuff. If there was a rash of clogged fuel injectors with everyone coming from a particular Costco gas station, then it may be that station in particular and possibly a leaky/contaminated fuel reservoir at that station, not the gas itself. It's so hard to say. There have been many cases of gas stations having thier fuel contaminated with water and debris due to cracks in the underground tanks.

In regards to pinging or engine detonation, when you get it, you know it. It's not all that subtle, and it only really comes into play under heavy load. It's a deep clammor sound that just doesn't sound healthy (and it's not for an engine). If you're hearing a rattle sound from the engine under slight load, that's probably the same thing I have in my 99 2WD RX, which is noise coming from the valve train. I attribute that to the fact these engines use mechanical lifters with no lash adjustment. Carbon build up on the valves and gunk build up on the valve train can cause the valves to not seat as deep as they should allowing a little bit of slop in the system, and hence the noise. I'm trying to run some injector/valve cleaner through my gas, then going to use Auto-RX to clean up the internals. I'll let you know if this quiets things down.

In short, all you need to run is good clean regular gas in the 1MZ-FE engine, and as long as you have good tire pressure, everything well lubed and maintenanced, you should get as good of gas mileage as possible. I got 26mpg on a nice long straight flat road the other weekend, and that's on pump regular.