I use Amoco Ultimate in everything with an engine, not because it's 93 oct, but because it is the cleanest burning fuel around. I have the crystal clear formulation in my area.

I want to know if premium gasoline causes a break-down in oil composition more quickly compared to regular 87 octane gasoline.

Anyone have any insight to this?

 

Unless an engine has serious issues, neither blend of gasoline should have any adverse affect on the lube oil within the manufacturer's recommended oil drain interval.

 

Using premium fuel in an engine that is recommended and designed for 87 octane, in extremes, could have an adverse effect on the oil. In an engine that is designed for regular unleaded, using premium will result in a slower formation of the flame front during combustion. It would be equal to running the engine in a retarded timing position. Because the flame front is slow to form, it doesn't burn as clean as the proper fuel would. There is generally a drop in fuel mileage and usually the "felt" performance gains are negative rather than positive. The unburned fuel will deposit more contaminates on the cylinder walls and it can also develope hot spots in the engine. The difference in the two fuels is the basic amount of Heptane, which is a seven length chain molecule, which becomes unstable during compression and helping to ignite the fuel charge. There is no more energy, as such, available in a higher octane fuel in an engine designed for 87 octane.
It all comes back to following the manufacturers recommendations. Trying to improve things by doing something different usually ends up causing a shorter engine life. Additives are not necessary with todays engines, higher than recommended octane doesn't help, different than recommended basestock oils, etc are jokes we play on ourselves. If you want the best for your baby, follow your owners manual, after all, they made the engine and all of the components, they know what is best for their product.

 

But isn't the owner's manual biased from the pure engineering recommendations by the changes made after legal, CAFE, and other reviews? Also, they make no account for the engine possibly needing a thicker oil in its oil age, that is very high mileage. I really don't trust the owner's manual.

BTW, I use a midgrade fuel (90 octane) in one vehicle, but only to prevent spark knock. The timing is right on and the car has been cleaned out in more ways than one (Italian tune up, water through intake, and about 5000 miles of fuel system cleaner).

 

One time in the past I spoke with a BP gasoline tech and he told me that it is a myth that unburned fuel can occurr when using 93 octane. He said it all burn completely, and that their crystal clear formulation is the cleanest burning fuel availble on the market, (even before the additives are put in)

It all comes down to "who the hell really knows". It's all a game of taking chances and learning from experience.

I will say there isn't one old fart out there I know who has told me they only use Crystal Clear ULtimate in their cars. My best friends grandfather past away recently and had a station wagon which was handed down to my friends parents...this war waggon has just ovefr 300,000 miles with no engine rebuild and used only Amoco ULtimate and penzoil conventional oil.

 

grbr95, Most of the gasoline in this area is either Mobil/Exxon or Valero. It doesn't matter if you are in a Chevron, BP, Amoco, Shamrock, Texaco, Speedway, etc., it comes from either gas terminal. The add packs are put in the trucks when they fill up at the terminal. Might also want to look at the color of the lids at the station where you fill up. If they have red, white, and blue lids, when you buy the mid-grade fuel-you are actually buying a mid-grade fuel. If there are only two colors of lids, regular and premium are mixed at the pump to equate the octane of the mid-grade. I have found that the mixed fuel sucks and fuel mileage suffers.

TP, quit being so cynical. The auto manufacturers are on a mission that they really don't want to be a part of anyway. Dear Uncle Sammy is trying to get them to warranty the emmissions systems for 150,000 miles. This means there can be no oil burner, no worn out engines, etc. The oils and fuels today are being formulated to hit this mandate. I can see 100,000 miles but 150,000 is going to be tough. I can see the day when you won't have access to the engine and the dealers will be doing all of the servicing. I don't see that there is an alternative. If you have an engine that is pinging/knocking, you might want to look at the knock sensor. Some of these use a pizo(sp) sensor and in my opinion are worthless.

 

It's very hard to believe that statement by the BP representative. If it were true, people would fill up with their gasoline before taking a second emission test. Under usual conditions, some small amount fuel will stay unburned, and this shows up as HC or CO on test reports.

Personally, I use whatever is specified, unless there is pinging. One of my car was a dog with stock advance, but it came alive with a few extra degrees, and I concluded that the improvement was worth the extra expense of 92 octane.

I recommend you to compute your mpg with different gasolines, and see if ultimate gasoline gives you any benefit.

 

I sort of see the point... Hmm I may need to reconsider my using premium fuel. This may be over kill on my vehicles.

 

Thanks for the tip on the knock sensor. I hope you are wrong about the dealer only servicing of cars, but it seems like an Orwellian path that we can't get off of. The problem is between the CAFE fuel economy requirements and the 100,000 (and likely soon to be 150,000) emissions system warranty requirements, the manufacturer is between a rock and a hard place and the motor oil is getting squeezed down a narrow path that appears to be full of compromise. Also, if they cannot tolerate oil burners (or presumably consumption) they are a long way off from the target because I frequently hear that 1 quart per 1000 miles is not considered excess consumption by auto manufacturers. How are they going to do it, except to have tighter controls on the manufacturering process? Even then, what the auto company cannot control is the person who will floor a cold engine and make it into a fogger. Oh well, looks like I will need to get into the classic automobile and truck hobby as I don't want to drive most of the new cars the big three are putting out.