Question from a newbie. I just purchased a '98 Maxima SE 5 speed with a 110,000 miles from its original owner. A dedicated Maxima 5 speed owner for many years, this fellow was a non stop highway driving salesman who used regular unleaded gas. The car is in exceptionally fine condition for the mileage and to my way of thinking, drives very well with good performance. Having read the comments and links provided in the FAQ section about using premium fuel, I'm wondering if there is anything to be gained from starting to use premium at this late stage if the car has spent the first 110,000 miles of its life running on regular unleaded?

 

Regardless of what you'll gain, the manual for this car specifally says to use 91octane or higher. Using anything less is simply bad. Start puting in 91 or higher now and don't use anything less.

 

 

I think most everyone here will say the same thing about gasoline. Use the 91 or higher octane gasoline......

 

That is why I posed the question. After reading the FAQ I understand that it is accepted as law that you use premium fuel. However, since my particular car has gone such an extended time and distance "breaking this law" and apparently, not overtly appearing to suffer from it, I was curious whether the normally expected benefits from using premium would still occur by switching at this late date?
Does the regular gas, over time, "coat" the injectors or other parts of the engine so that the only way to achieve its "proper" performance is to start replacing many parts and then run premium OR can you simply start using premium anytime and undo all the years of running regular and immediately see benefits (such as better performance or better fuel mileage or something else)?
I'm not questioning the factory designation of using premium, only asking about what may have happened to the car from its prolonged use of regular thus far and whether that can be overcome by simply switching to premium now? Also, could there be any possible adverse effects (on fuel related parts or performance) in switching to premium if a car has been running regular for so long? Thanks.

 

Your engine parts are fine. Just ungrading to 91 will let the engine advance the timing to where it should be in the first place. That could give you 5-7hp and much more throttle response. Try a tank, you'll never go back!!

 

Ya i down graded o 89 for about 2 weeks and my injectors ticked aot and my car didnt run smooth , id recomend 93 but gas prices are wayy up there, 1.85 for 91 in CT

 

my car runs totally different on the two grades of gasoline.. for the extra 3 bux on a full tank i'll stick to super.

 

Maybe you should re-phrase and ask yourself the question this way:

Do I want to have and use all or most of the 190 hp that the car is capable of producing?

DW

 

That maybe the question you and others wish to answer, however, that is not the questions I was asking. I've already stated that I am not in any way questioning the reasons for using of premium fuel.
I'll try asking again, but, this time answer them myself and suggest that if you disagree with my conclusions based upon the posts here, that you post the correct info. Thanks.
1. Are there any long term consequences that I should be aware of given that the previous owner used regular for 110,000 miles, even though the car appears to still run fine? I'm gathering the answer is none.
2. Will using premium now, even after prolonged use of regular still give me the normally expected gains from switching from regular to premium on a car with much lower mileage? I'm assuming the answer is yes.
3. Can switching to premium after prolonged use of regular have any possible adverse effects? I'm gathering the answer is no.

 

The damage that used to be done to engines when the octane was too low (pinging) is no longer a problem. As long as you don't hear pinging under heavy load (hard acceleration at low rpm), I can't imagine how any damage could be done.

 

1. No one knows for sure, we would just be guessing. Realistically, probably not.
2. Yes
3. No

 

OK, thank you.