Just test drove a 2003 TL where the owner used regular gas

I just got back from a 2 hr test drive of a 2003 TL with 52,000 miles. I plan to buy this car tomorrow if everything else checks out for $17,100. The current owner said he always used regular (Octane 87) gas. I know the computer will change the timing to avoid knocking, but will this, in the long term, cause engine problems and vibration and future problems? Also the front motor mount was broken - could motor vibration from low grade gas cause this?

On the test drive I got 29 mpg with the ac on. Also, a 0 - 60 mph acceleration test gave only 9.4 seconds - rather slow. Could the timing adjustment cause the car to run this slow? would the gas milage go up and acceleration be better with a higher grade fuel?

Thanks for any advice on this, Rick yes the vehicles on board computer will retard the timing a little to avoid knocking but as far as knowing if it will have a negative affect on anything in a long term is hard to say. with the vehicles on board computer tweaking & adjusting timing and fuel mixture it should even on a low 87 octane should still run pretty smooth and not vibrate so bad that it damages a moter mount

but then again i wouldent completly rule it out either or it may of been faulty too as far as your gas mileage and performance is concerned that can get better once you switch over to a premium 94 octane fuel something good to use? if you live in u.s.a chevron with techron is a very good one sunoco, shell start using high quality fuells and let us know.

"Rick" wrote in message news: snipped-for-privacy@y41g2000cwy.googlegroups.com...

The use of lower than specified octane gasoline rarely causes long term problems for modern engines because of the use of knock detectors. It can be a very bad thing in engines without knock detectors because of the amount of damage that can be done. See

for a better overview.

The motor mount is not going to be because of the gasoline, but if the tranny is a manual it may be an indication of harsh shifting - dumping the clutch when the engine is revved too high. That would make me worry about the clutch and maybe even the way the car has been treated overall. Combining harsh treatment with cheaping out (as seen in the gasoline area) is a bad idea. In this vein, have you removed the oil filler cap and peeked inside the valve cover with a flashlight? Where the oil has drained away from the rocker assembly you should see silver metal. The more brown it is (not because of remaining oil film) the poorer the oil upkeep has been. Some brown varnish is acceptable but in a 2003 it should be only the lightest tinge. Failing that check disqualifies the car when I'm buying. Ditto for any trace of rust in the cooling system, either when you look in the coolant reservoir or (if the engine is cool) if you remove the radiator cap and run a finger around the inside of the radiator neck. Anyway, for examples of what you should see check out

and from . If you see something like the picture on the right side of that page don't even think of buying it. Low octane gasoline will definitely slow down the full throttle acceleration, as the knock sensor is pretty heavy-handed in retarding the timing if it hears a ping. After all, it has an engine to protect. It usually won't affect the throttle response in normal driving. Many people report better fuel economy when running premium in an engine that is designed to use it, and most report enough better economy to make up the 6% price difference. If premium brings the 29 mpg up to 31 mpg you are paying the same amount for gasoline.

Mike

I would ask the owner when they are using regular instead of premium. If they say they are doing it to save money, then I would run away. You have to wonder if they didn't try cutting other corners, like regular maintenance, to save money.

------------- Alex

Hmmm, someone buys an expensive new car and then run the cheapest gas they can find ?????? I would keep looking. You should be able to find excellent pampered used TLs around. A pampered car is the one you want, not the car of a cheap skate.

John

Referencing back to my comments a week ago related to using regular (below 91 octane) fuel in high compression engines, you are relying on the knock sensor and computer to detect knock (detonation) and reduce either timing, fuel flow or both FAST ENOUGH to prevent damage to the engine. If that process fails, even one second of severe detonation can essentially destroy major components and require a total rebuild. Not cheap. To my knowledge, current engine fuel management systems do not have the capability to directly determine the octane of the fuel being delivered to the engine and control the engine accordingly. Today, the engine settings are adjusted by the results occuring inside the engine as it operates, all after the fact.

If you want performance, put in the recommended fuel and enjoy. If you want economy, avoid hi-compression engines in general and the high horse-power options in whatever you are interested in and enjoy.

One othe point, higher octane fuels typically are blended from stocks and additives that combined have a slightly lower specific energy content per volume. Ironically, then, in tests on otherwise identical engines using fixed timing, mixture ratios, the lower octane fuel will produce better fuel economy UNLESS the timing or octane is causing detonation, in which case, it will be worse, potentially far worse.

While the difference is small, it is measureable in a tightly controlled test.

Paul

You guys are kidding, right? If you think the majority of TL owners are pumping Premium gas into their cars these days, you're not paying attention at the pumps. Premium gas sales are WAY down. And then there's the cheating that goes on at gas stations where that 93 octane pump doesn't actually dispense

93 octane gas. Like the Accord, the TL will run OK on 87 octane. I haven't seen any reports of engine problems due to detonation for the TL or any other car not used for racing. A service record for the car is another matter entirely.