Can I use 87 octane gas in my 1993 Lexus SC300 - manual says use 91 octane?

Question

When I use 87 octane, it works fine withou a knock. am I hurting the engine. I am trying to save $$$>

Answer 1

It's important to use the recommended fuel for your vehicle. Your spark plugs were made for 91 octane, so they go off evenly with 91 octane. If you are using 87 octane, you might be spending less at the pump, but your spark plugs are not firing evenly with the gas you are using. What you are doing is making your vehicle use more power and getting less outcome. You're also losing fuel efficiency, so you're going to have to fill up more often. You might think you're saving money, but in fact, you're ending up paying more economically.

Answer 2

Depending on where you live you may be able to get away with it. Typically if the car requires 91 you can get away with 87 in the winter months, 89 spring and fall and 91 in the summer only. If you're trying to save money an SC300 probably isn't a real great choice though, I can't imagine insurance on one of those is cheap since it's a non turbo Supra with a lexus badge. Also checking your tire pressure regularly and keeping up on oil changes and other maintenance can save you far more in the long run on improved fuel economy.

Answer 3

1993 Lexus Sc300

Answer 4

In the long run you will. The reason is that some engines run on the extra high compression. I forgot but some small trucks you are NOT supposed to run on ethyl, being that they are low compression engines. You might save now, but pay later.

Here is what you do.
1. Take at least two tankfuls of gas in your car and get an accurate mpg for your vehicle. Then do an oil change but with SYNTHETIC oil. After 1000 miles do a two tankful fillup and get the mpg of your vehicle. If you figure right you will see you are saving money on gas. Also, you do not have to change oil till 6 months. But I tell everyone, change the oil filter at 3 months and just pour what oil you can back. If you go to Walmart they sell the buy 5 qt bottle and pay for 4 quarts.

2, Buy some Plus 4 sparkplugs. They last longer, get a hotter spark so detonate the gas cleaner and better, and therefore giving you just a wee bit more of power. Yes, they run 4 times more than regular plugs, BUT they last as long. And you have to look at the money you save in a year or two.

3. Buy your spark plug wires like at auto zone. Lifetime warranty and change them when you need.

Now me, I change the oil ONCE a year but every three or two months I do a quick filter change. I got a 92 Ford Explorer with 230,000 plus and still running good. The only thing I had to change was the power steering unit, power steering lines, and oil pump. Then I noticed a water leak in the water pump, starting so I will change that. My philosophy spend now. Save later. Once you see the money saved with the syn oil, like me, you will just use it for any vehicle knowing you are automatically saving money.

Answer 5

you better use what the manufactor recommends even though you don't hear it pinging the newer cars have a anti knock sensor that retards the timing on the engine when it gets into a pinging situation so you will be hurting your performance and gas mileage by using the 87 octane.

Answer 6

1993 Sc300

Answer 7

You may be okay, but it's hard to tell. The fuel may be stable enough to not cause a knock, but it may be igniting faster than it should, which will raise emissions levels, poison the catalytic converter and may lead to excessive carbon build up and spark plug fouling. I would recommend staying with the 91, even without the knock.

Answer 8

The answer is YES, you can use 87 octane rating.

Just be mindful of any pinging from the lower grade fuel....your engine management system has a knock sensor
and will retard timing automatically.

The effect from using 87 grade is a slightly reduced off idle response...

Answer 9

i own a repair shop and been a mechanic for 36 years,believe me when i say its not hurting anything on it,most of the lower brands of gas now runs just as well as anything else will,the only difference is the amount of money you actually have to pay out when you do a fill up,other than that 99% of the time you cant tell the difference in the two ,good luck i hope this helps.

Answer 10

NOPE

it will run but the oxygen sensors will get all messed up, the var will run less efficintly and cost you more down the road as you mess up the mass air flow sensors and other sensitive electronics.