Premium unleaded necessary?

lexus
300
sc

#1

I recently purchased a 1995 Lexus SC300 from my mechanic. The car has very low mileage and is great condition (after some work by my mechanic)…My question is this…is it REALLY necessary to use only premium unleaded gas in this car? It’s really expensive and I’ve had others tell me that it really isn’t necessary that I could use regular unleaded every other time for example. What do you think?


#2

And you did not think to ask your mechanic this question? Is this potentialy a case where you do not want the doctor to know what you are really doing?

Question has been asked a thousand times. You could use the search feature.


#3

You bought a premium car, why skimp on the fuel needed to fill it? If your owner’s manual says it requires premium, use it, if it recommends it, use it, if it says 87 octane, you’ll be ok using regular.


#4

This horse has been beat to death…In the search window, type “premium fuel” …


#5

I will revise my answer.

The car is at the end of its life anyway being 15+ years old. Unless you hear undue knocking using regular I would not worry much as this car does not have lots of life left liekly.


#6

Not much love on the “I bought an expensive car and want to buy cheap gas” front, is
there?
The truth is you need to buy the octane level gasoline the dumb old engineers who designed your car and who work for Lexus say your car needs. If that means you could have saved twelve cents a gallon on each fill up, too bad for you.


#7

You bought a high end car, expect to pay for correspondingly high end upkeep costs.


#8

Check your owner’s manual. It will say that premium fuel is either recommended or else must be used. If recommended, you can use 87 octane as your engine will have a knock sensor that will adjust the spark timing to prevent detonation.

If you can use 87 octane, that is fortunate as you will need the money to eventually change the cam timing belt at 90,000 miles. How does $500 sound?


#9

The owner’s manual will tell you if premium is recommended, required, or neither.

If required, not using premium could damage the engine.

If recommended, not using it will reduce power and mileage. It may actually cost you more per mile using regular.

If it does not say, then don’t waste your money, it will not give you better mileage, longer engine life or more power.


#10

You didn’t note the engine specifics, but the short answer is – it depends. Toyota made several variations of its basic engines.

The 3-L 2JZ-FSE inline I-6 uses the same direct injection principle as the smaller 1JZ version running an 11:1 compression ratio, but runs an even higher 11.3:1.

The 4.0 L 1UZ-FE V-8 debuted in 1989 in the first generation Lexus LS 400/Toyota Celsior and the engine was progressively released across a number of other models in the Toyota/Lexus range. In its standard, original trim, it runs a 10:1 compression ratio. The engine was slightly revised in 1995 with lighter connecting rods and pistons and an increased compression ratio to 10.4:1. I believe both are turpo-charged.

The general rule is, you can use 87 octane gas up to around a compression ratio of 10:1. Once you cross over that ratio, you will likely need a higher octane. However Toyota has done some wizzardry with the computer tweaking of these engines which may make it possible to use 87 octane. It’s a close call. Bottom line – go with the manual.


#11

If you can’t afford the correct gas, then you can’t afford the correct maintenance either.


#12

Most seem to agree that you should stick with the recommended level. But, I don’t use premium in my 1997 Licoln and it runs perfectly and has for the many years I’ve owned it. Now with over 100,000 miles I should be due for new plugs, but there is no sigh that I need them. So here is one vote for sticking with low octane unless your car’s engine perfomance signals you that it want’s the higher octane.


#13

timing belt should have been changed atleast twice already due to age


#14

The oil companies go through a lot of trouble to make and market “Premium Fuel”. SOMEBODY has to buy it. That somebody is YOU !!!

When that engine is used in a car that is badged “Toyota” it runs FINE on regular…


#15

Only problem with that argument. The 2JZ-GE engine found in the SC300 was never used in a North American-spec Toyota.