How to read motor oil specs for fuel efficiency?

[AlexVLZ]

Hi

There are so many brands, models and specs, but does someone got a key to reading these. Honestly I get lost.

I got a Nissan Pathfinder R51 (I love it), not exactly a fuel efficient vehicle, and now I am trying to reduce the oil consumption. This weekend I wish to change the motor oil.

thanks

Alex

[Fat Charlie]

You're trying for two opposite goals: you want a lower weight oil for fuel efficiency, and probably a higher weight oil to reduce oil consumption. The main job of oil is to lube the engine, so I'd worry more about consumption- it doesn't matter what slight improvement you get in gas mileage you get if you're always adding oil.

[AlexVLZ]

Hi,

What do you mean with engine oil consumption in relation to a thinner oil?

I was thinking about picking up this ELF 5w30 Evolution that they advertise that reduces "increases up to 8% fuel consumption" which I know is pure marketing, but at least it mentions it, others don't --so there might be some truth there. Second option is this 5w40.

thanks

Alex

Originally Posted by Fat Charlie

You're trying for two opposite goals: you want a lower weight oil for fuel efficiency, and probably a higher weight oil to reduce oil consumption. The main job of oil is to lube the engine, so I'd worry more about consumption- it doesn't matter what slight improvement you get in gas mileage you get if you're always adding oil.

[Fat Charlie]

If your engine is consuming oil then it's got problems. Metal has been wearing, seals are starting to leak and a more flowable oil will get through those gaps more easily than a thicker oil.

[some_other_dave]

You said you were trying to reduce oil consumption. Did you mean fuel consumption?

If it's using oil, it is most likely burning it. So oil is getting into the combustion chamber somehow. A thinner oil will flow more easily (that's what "thinner" means) and so more of it will leak into the chamber, getting burned. So the vehicle will probably use more oil if you go to a thinner one.

A thinner oil is easier to pump around, though, so it will give you (very slightly!) better fuel economy. I'm not sure the difference will be enough to measure, though.

What oil weight is called for by the owner's manual? There is a specified oil, or more likely a range of oils, and it's best to stick to that range. If you're looking to keep oil use down, go for something on the thicker (higher numbers) end of that range, and if you're looking for best fuel economy, use something on the thinner end of that range.

....Then again, driving style will give you a lot more MPGs than thinner oil ever could, so it might be best to concentrate on that rather than worry about which oil to use...

-soD

[dirtydave]

Changing to expensive high MPG oil wont make but 1% difference.