Honda J35 vs. Acura J37 - Fuel Requirements

[Number_35]

Friends are looking at a 2013 Acura MDX with the Honda J37 engine.

Premium (Octane 91) gasoline is either recommended or required, as opposed to the J35 engine in the Pilot, which is fine running on regular (Octane 87).

J35 compression ratio = 10.0:1

J37 compression ratio = 11.2:1

Would it be OK to run the J37 on regular? That is, is the engine equipped with a knock sensor that would tell the ECU to retard the timing to prevent preignition? I realize power and fuel economy would suffer, but would running regular harm the engine?

 

[rijndael]

Here's the knock sensor: https://www.acurapartswarehouse.com...xtra2=KA 6AT&filter=()&location=pd:1586077,10

 

[Nessism1]

I'd run the recommended fuel. It's unknown how much adjustment the ignition system has for knock. It may be enough to compensate for regular fuel, but then again, maybe not. Best to not take chances unless reliable technical information is available. Oh, and if Honda/Acura felt that regular fuel was okay, I suspect they would state as much.

 

[fantastic]

Much more demand on the J37. Heavier, higher compression, etc. At the very least you'd not be getting the full power out of the engine. At the most, possible, blowing a head gasket or something from running hotter. I'd expect a luxury car to adapt if driven within reason. Go outside of that boundary on 87 not certain. There was the recent video discussion about premium fuel potentially reducing engine/injector wear so there may be more benefits to using premium fuel.

 

[wag123]

If they can't afford the higher octane/higher priced fuel they should be looking at something else.

 

[andrew_j]

The power loss is actually noticeable and the MPG suffers a bit on 3.7. I have owned both. The MPG loss made it a wash.

I own a Acura (RDX) with 3.5 which requires premium however seems content with regular. I also own the Pilot

 

[Number_35]

If they can't afford the higher octane/higher priced fuel they should be looking at something else.

It gets pricey here - 15¢ to 20¢ per litre x 60 or 70 litres per fill adds up to a lot of money over a year.

 

[andrew_j]

On a side note that vehicle is an absolute fuel pig.

 

[Number_35]

On a side note that vehicle is an absolute fuel pig.

The EPA says it's slightly better (18 MPG vs. 17) than the 2007 Pilot it might replace, but that would be offset by the need for premium.

 

[fantastic]

On a side note that vehicle is an absolute fuel pig.

Had to go look on fuelly to compare to my Volvo 3.2L & sure enough the Acura 3.7L is 1.35 mpg less. Now that isn't apples to apples though.

 

[Number_35]

Had to go look on fuelly to compare to my Volvo 3.2L & sure enough the Acura 3.7L is 1.35 mpg less. Now that isn't apples to apples though.

It's not bad given the MDX's capabilities - but might be worse here with our cold weather.

 

[NormanBuntz]

To me, if you want to get the most out of your engine, use top tier premium gas.

 

[Number_35]

Update: Our friends bought the Acura MDX today, and will use premium fuel in it. Per the first owner, it's been run on premium its whole life to date.

They plan to use the vehicle pretty much for out-of-town trips, perhaps 10,000 km per year. The difference in fuel cost will be inconsequential.

 

[andrew_j]

Update: Our friends bought the Acura MDX today, and will use premium fuel in it. Per the first owner, it's been run on premium its whole life to date.

They plan to use the vehicle pretty much for out-of-town trips, perhaps 10,000 km per year. The difference in fuel cost will be inconsequential.

That’s great. Make sure oil level is checked initially every 1000 miles. This engine had a 8 yr/125k extended warranty for oil consumption due to improper rings.


My brother had exact vehicle and it did not qualify so he was adding quart oil every 1500 miles and he/daughter would forget.