unleaded regular gas

gselby

I recently purchased a used Lexus GS300 with 22,000 miles. The book calls for 91 octane rated gasoline. I have used 2 tanks of 87 octane rated gas with no noticable problems. What are the consequences, if any, of using unleaded regular?

Mr_Shiftright

Probably nothing drastic other than deteriorated performance. Your engine will adjust to the lower octane by retarding timing, thereby giving you less power and probably fewer miles per gallon. So you may not end up saving much of anything by using the lower octane. You can experiment if you wish, recording mileage with both lower and higher octane, and also seeing if you like the difference in performance between 87 and 91 octane. It can make a big difference, depending on the car and what you are doing with it.

cutehumor

Lexus is a very expensive car, why pay the big bucks for a luxury car even if it is used then try to save 20 cents a gallon by using regular instead of premium? Maybe you would save a couple of hundred, but a Lexus is a big investment.

rayfbaird

The government says there is as much power in regular as in super. The Octane retards the spark. If the engine is designed to spark before Top Dead center it needs higher octane. Use what the engine is designed for.

q45man

"If the engine is designed to spark before Top Dead center it needs higher octane' Say what?
All cars fire the spark plugs BTDC some 1-2 others 15-20.... necessary to let the fuel burn before 15-20 degrees ATDC.
The amount of timing advance is a function of the distance of spark plug from the bore side and the fuel AF ratio and the temperature of piston and chamber walls.
In fact Premium usually has 3% less BTU than regular [the addditives slow down the burn].

joe3891

Use what the owners manual says to use or you are looking for trouble,use 87 in an emergency only.
Trust me.

Mr_Shiftright

As long as the car is not pinging, I really don't see the harm in using 87...I feel sure that your car's ECU "map" can retard the spark at least to the point of handling 87 octane with no problem. Maybe if you used gas so low in octane that the engine could not retard enough, that would be troublesome.

rayfbaird

I got my information from my Subaru owner's manual and government information about Octane. The higher Octane is not as volatile

meca2

I found a very good article on octane and how it is figured and what is means:
www.prime-mover.org/Engines/GArticles/octane.html
I hope this works.

dlh4

A question for the general public concerning a fuel additive called Gas Saver that injects microscopic amounts of platinum into the vacuum line and then to the cylinders to increase fuel combustion from approx. 70% burn to 90% burn, essentially increasing fuel economy by 22% or more. Has anyone had any experience with this additive? How would it affect a new car warranty? I have read that this additive would actually help by increasing power and therefore reducing the octane requirements for a luxury car that drinks premium. thanks for any info.

swschrad

all kinds of injectables into the vacuum line have been thrown at the "problem" of gas mileage. why? because over the long haul, it's a great profit that works on the placebo effect. consumer and insurance test labs invariably report the devices are very efficient... at separating a fool from their money. if BP or Chevron hit upon something that worked, they would use it, guaranteed. I bet the ads never gave a percentage of platinum per cylinder-full, either. probably just had a guy on the loading dock with a platinum wedding band and figured that's all the exposure they'd need -- platinum is expensive.

namfflow

If your car calls for high octane then use it. Yes, today's vehicles will adjust the timing to compensate for the lower octane and prevent pinging but you lose the performance you paid for. Quite frankly you'll get better performance and gas mileage using the correct fuel.

I used to have Mopar turbos. They called for high octane. Being a cheapskate I use 87 for a long time because I didn't hear any pinging. Then I found out about the computer adjustment. I switched back to the 92 octane and got both better performance and mileage. Enough of an increase in mileage that I actually saved money using 92 octane.

Higher octane is designed to resist burning to prevent detonation in higher compressioned vehicles. Use it if it is what is called for. If your vehicle calles for 87 use it, use of higher octane than you need will hurt performance and waste money and increase emissions.

Again, use what is called out for your vehicle.

Mr_Shiftright

Many engine computers will now adjust for lower octane, but many will not automatically raise timing to take advantage of higher octane (higher than called for in ;your owner's manual). so it really is a waste, in most cases, to put in 92 octane if your car is only mapped for 89

mrdetailer

and your car is designed for regular, go to a mechanics shop, pay about $100.00 to get a fuel injector de-carbonization. I had an auto that ran smoother on premium until I cleaned the fuel injectors. Now it only uses regular.