Mike_02GT_02R6 Posted January 7, 2006 Share Posted January 7, 2006 I've always been curious about that real differences between the different gas grades. I know little about them, and most of my knowledge is from what I hear the different gas companies advertising their gas as. 87 grade is the generic gas grade. 92-94 have special additives and are meant for more high reving engines, or high performance engines. I've also heard that 92-94 grades burn more clean and efficiently. So does that mean that if I use 87grade the fuel is not going to burn as well? And especially advertisied by chevron, their additives 'clean your engine' while using their product. Does anyone know what that actually mean? Cleaning your injectors? Spark plugs? Cylinder walls? Exhaust valves? I just recently purchased my 02 GT 2.5 with 34k miles and one previous owner with no idea what they used for gas. I've had this half-baked idea that if I use 3-4 tanks of cheveron 92 it should 'clean out my system'. But I dont have any factual evidence that what I'm doing will actually work. And my subaru manual calls for 89grade gas, so will running 92 hurt anything? So does anyone know that actual differences between these grades? Link to comment Share on other sites More sharing options...
springnr Posted January 7, 2006 Share Posted January 7, 2006 Use the recomended Octane. Top Tier Gasoline. Link to comment Share on other sites More sharing options...
Xenonk Posted January 7, 2006 Share Posted January 7, 2006 discussion finished Keefe Link to comment Share on other sites More sharing options...
Mike_02GT_02R6 Posted January 7, 2006 Author Share Posted January 7, 2006 Use the recomended Octane. Top Tier Gasoline. great info! It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio. perfectly said and now I understand what these different ratings mean. But I am still wondering about these so called detergents that 'clean your engine'. Any info on that? Link to comment Share on other sites More sharing options...
rporter Posted January 7, 2006 Share Posted January 7, 2006 Mostly marketing crapola. A certain level of detergents is mandated, and is in all gas grades. Having "more" in certain grades & brands is nothing but marketing stuff. I agree....end of topic. I swear, if all car forums didn't have multiple threads on what gas or oil to use, or how to break in the car, the number of posts would drop by at least 50% Ron Link to comment Share on other sites More sharing options...
deneb Posted January 9, 2006 Share Posted January 9, 2006 Anyone have any data to support whether 'top - tier' fuels, with their higher level of detergents, do a better job of keeping engines clean than fuels with the minimum level of additives? Why would automakers specify higher levels of detergents if the minimum level was sufficient? Link to comment Share on other sites More sharing options...
legacysteve68 Posted January 9, 2006 Share Posted January 9, 2006 good read! Link to comment Share on other sites More sharing options...
rporter Posted January 9, 2006 Share Posted January 9, 2006 Anyone have any data to support whether 'top - tier' fuels, with their higher level of detergents, do a better job of keeping engines clean than fuels with the minimum level of additives? Why would automakers specify higher levels of detergents if the minimum level was sufficient? Mfrs don't specify higher levels of detergent additives, they only specify recommended octane levels. Every car built in the last 15-20 yesr will run on 87 octane, admittedly with lower power levels. Any additional additives lower the BTU level of fuels, which is where the pwer and mileage are at, apart from octane needs. Ron Link to comment Share on other sites More sharing options...
deneb Posted January 9, 2006 Share Posted January 9, 2006 OK, but my question still stands. In fact, it seems more relevant now with you stating that additional levels 'lower the BTU level of fuels which is where the power and mileage are at'. Are manufacturers sacrificing octane for higher levels (and the resulting drop in mileage) of detergents? Furthermore, how is it that I can go to a Chevron station (top tier) and they have 87 unleaded, whereas a non top tier fuel at a competing station also has 87 octane? Link to comment Share on other sites More sharing options...
rporter Posted January 9, 2006 Share Posted January 9, 2006 OK, but my question still stands. In fact, it seems more relevant now with you stating that additional levels 'lower the BTU level of fuels which is where the power and mileage are at'. Are manufacturers sacrificing octane for higher levels (and the resulting drop in mileage) of detergents? Furthermore, how is it that I can go to a Chevron station (top tier) and they have 87 unleaded, whereas a non top tier fuel at a competing station also has 87 octane? I don't totally understand your question, but octane level and BTU levels are not directly related. Power comes form the BTU level. Octane is purely the ability to resist detonation/pinging. IMHO, higher octane is a band-aid, it has no power-producing capacity in and of itself. The more additives that you add to pure gasoline, for octane improvement or whatever, the lower the BTU level. As pure gasoline is the "wonder fuel" (as described by Bob Lutz) and no other additive packs as much bang. Ron Link to comment Share on other sites More sharing options...
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