Anyone use regular gas in their Si?

[PowerPerLiter]

I just realized ive been responding in the wrong thread somehow. Lol. Doesn't matter still applies Haha

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[amirza786]

I just realized ive been responding in the wrong thread somehow. Lol. Doesn't matter still applies Haha

LOL that's hilarious!

 

[tinyman392]

The difference in "recommended" and "required" is just a difference in vocabulary geared toward the client base of who the manufacturer is trying to sell to.

"I ain't buying no Honda that needs premium!" Recommended.

"Well my Lexus NEEDS the most expensive gas because it's special!" Required.

Both will run on whatever because of modern computers. And both were designed with premium in mind.

Do what you want. Less than 91 is ill advised.

Except if you bring your Lexus in for warranty repairs when it ran regular, it'll most likely have a voided warranty. If you bring in the Si, it will still retain its warranty.

 

[Gotch]

It seems your under the impression that I used 87 when I only used 91 (past tense, since I don't own the Si anymore). Anyway bro, enjoy your vacation, and get in the water. Vacations should be computer free!

Nope! Never crossed my mind that you would do such a thing! Just others asking the question....

 

[PowerPerLiter]

Except if you bring your Lexus in for warranty repairs when it ran regular, it'll most likely have a voided warranty. If you bring in the Si, it will still retain its warranty.

Lexus would not void warranty from running 87. That's laughable. Nobody really can. As a safety thing the car has to be operational using any common grade of unleaded.

 

[amirza786]

Except if you bring your Lexus in for warranty repairs when it ran regular, it'll most likely have a voided warranty. If you bring in the Si, it will still retain its warranty.

The ECU in the Lexus would do the same thing...it would pull timing if it detected 87 octane gas. It would run like crap, but the ECU would protect the engine as well

 

[REBELXSi]

I would not buy a car from a dealer who puts 87 in when 91 is recommended.

You have zero idea if your car came with 87 in it. The chances are, it did. It's no big deal.

 

[tinyman392]

Lexus would not void warranty from running 87. That's laughable. Nobody really can. As a safety thing the car has to be operational using any common grade of unleaded.

Do you have a source for that statement? If the manual says X is required and you use Y, then your engine gets damaged due to using Y, it seems pretty clear cut that they could void your warranty claim for that. I'd argue that it would be similar to having a BMW that requires BMW Longlife-01, but you use another brand of oil (that isn't BMW Longlife-01) but the same viscosity. It probably won't do any damage, but they could theoretically deny warranty claims related to engine lubrication if they find out.

The ECU in the Lexus would do the same thing...it would pull timing if it detected 87 octane gas. It would run like crap, but the ECU would protect the engine as well

I'm not saying that the Lexus engine won't pull timing to deal with the issue (or that it will damage the engine). I'm saying that if it were to cause damage that required a warrantied fix, Lexus might not cover it if they knew it used 87 when 91 was required (not recommended).

Edit: basically, if Lexus could prove that using a lower octane fuel could cause said damage, then they can deny the warranty claim.

 

[REBELXSi]

I’m on vacation for 4 days and it just boggles my mind that an Si owner would run 87 in their car... I’m actually in a happy place @amirza786 ! You know what? Throw whatever in your Si, even diesel. I’ve heard that you can gain 40lbs/ft stock running diesel!

LOL I'm pretty sure he wasn't advocating using 87 but simply saying (like I was) that it won't cause any damage if you did. There's a difference in saying something is OK and telling you to do it.

How long will this thread go on? The horse has been beaten to death and now we're shooting it.

 

[PowerPerLiter]

I just had a 34k mile 2015 rx350 engine replaced for a customer of mine that just scattered the short block for seemingly no reason. Piston gone. Valve dropped. Carnage.

I dealt with the warranty reps personally.

That's my source.

Not once did they even test the fuel at that stage of failure as they simply cannot prove it caused the failure. If anything it should chuck some codes up or shut off (a misfire is a different story, and even then ive had other customers put the wrong gas in, that needed injectors that still went right through).



Maintenance records were there and documented. No questions asked. Done.

 

[tinyman392]

I just had a 34k mile 2015 rx350 engine replaced for a customer of mine that just scattered the short block for seemingly no reason. Piston gone. Valve dropped. Carnage.

I dealt with the warranty reps personally.

That's my source.

Not once did they even test the fuel at that stage of failure as they simply cannot prove it caused the failure. If anything it should chuck some codes up or shut off (a misfire is a different story, and even then ive had other customers put the wrong gas in, that needed injectors that still went right through).



Maintenance records were there and documented. No questions asked. Done.

Lexus RX 350 requires 87 octane (from 2012 and onward).

Edit: it may recommend 91, but it requires 87. So even if they could prove fuel was the issue, it wouldn't have an affect on warranty.

Edit 2: my argument was simply that if a car required (not recommended) 91 octane and you put 87 octane in it and you bring it in for repairs that could be caused by improper fuel use, the service center could deny warranty claim solely based on that if they wanted to. Most (if not all) probably won't, but they are allowed to.

 

[Gino27]

eh... that's a widely discussed and disputed grey area.

https://en.wikipedia.org/wiki/Engine_knocking

The ECU will pull timing when it detects knock. Knock is pre-ignition or detonation at an unexpected time. Saying "zero damage will occur" paints quite the harmless picture. IMHO, if an engine is prone to knock, it's not running right and is going to have problems.

Now if someone only fed it regular, the timing would get adjusted kinda permanently (effectively enough). The engine would make less power and would be a sad example of how it can run on lower octane fuel.

I'd say giving the engine 91 octane is a minimum since some areas do not have 92 or higher available. Running the engine on 87 octane because "it will adjust to the fuel and back off timing...." is just a horrible idea.

So, my dad ran our Si on 87 for about 6 months. I'm hoping the ECU should've readjusted after 2 months on 93?

 

[PowerPerLiter]

So, my dad ran our Si on 87 for about 6 months. I'm hoping the ECU should've readjusted after 2 months on 93?

It should over time but the best thing to do would be to reset the computer to let it adjust for the different fuel.

 

[Memogiyi]

If I remember correctly turbocharged engines should always use higher octane fuel to ensure the catalytic converter runs more efficiently. Using lower octane may give you issues in the future with your Cat. Now if the car wasn’t turbocharged I don’t believe fuel octane would really make a difference to the cars performance.

I would not go below 91!

 

[amirza786]

If I remember correctly turbocharged engines should always use higher octane fuel to ensure the catalytic converter runs more efficiently. Using lower octane may give you issues in the future with your Cat. Now if the car wasn’t turbocharged I don’t believe fuel octane would really make a difference to the cars performance.

I would not go below 91!

That's not true. The regular turbo charged Civics as well as the 1.5T Accord both use regular unleaded, as well as the CR-V EX etc. Only the Civic Si, the CTR and the Accord Sport 2.0T use Premium. If you use Premium on these models, you are just wasting money as they do not benefit from Premium gasoline. Again, I am only referring to stock engines. Tuning them might change things