Using 'better' grade engine oil - is this OK?

[Matt UK]

Bit of a thick questions I know, but there you go.

If the oil spec for the car is 5w-30, would it be OK to use 5w-50?

[buggalugs]

No, 5-50 isn't better just different, get a good quality in the right grade to upgrade.

HTH

[Nick3point2]

5w50 isn't necessarily better than 5w30, it may be too thick at operating temperature and can affect fuel consumption and engine life.

Just stick to what the manufacturer state is correct.

[steveo3002]

id say no , its way thicker , dont go guessing at things thinking its a upgrade

the "w" number can go lower and thats a good thing as it means the oil will still be thin in cold weather so it gets round asap

[Nick3point2]

steveo3002 said:

the "w" number can go lower and thats a good thing as it means the oil will still be thin in cold weather so it gets round asap

Not necessarily, engine oil galleries/squirt jets/orifices are tuned to a specific viscosity range of oil, so thinner oil will give less of a head of pressure across a restriction which could starve parts of the engine.

Edited by Nick3point2 on Sunday 3rd July 16:57

[McSam]

Nick3point2 said:

Not necessarily, engine oil galleries/squirt jets/orifices are tuned to a specific viscosity range of oil, so thinner oil will give less of a head of pressure across a restriction which could starve parts of the engine.

Yep. The engine's designed for a very specific oil grade and the dependency on that is very high, so sticking to that grade in the best possible quality oil will be the best option.

[mrmr96]

Matt UK said:

Bit of a thick questions I know, but there you go.

If the oil spec for the car is 5w-30, would it be OK to use 5w-50?

No, that won't be ok.

Oil gets less viscous when hot vs when cold. The numbers relate to how thick (viscous) the oil is at specific temperatures. The higher the number the thicker the oil at a given temp.

You should use the grade specified by the manufacturer unless you've made extensive modifications to the engine and you know what you're doing. (For example if you're using a car on track and you know the engine temps are higher than on the road then you may choose to use an oil with higher grade number so that it's the right viscocity despite the higher temp. I.e. if you used the recommended grade then it would be too thin, because the temp is higher than standard.)

[Prawo Jazdy]

Hmmm. My car's handbook says it should have either 5W-30 or 10W-30 (depending on the temperature range).

At a main dealer service, they put 10W-40 in it. The Opie Oils thread on here recommended 5W-40 to someone with the same car.

I'm left confused. Should I have taken issue with the dealer using a different oil from what the manufacturer state?

[McSam]

Prawo Jazdy said:

Hmmm. My car's handbook says it should have either 5W-30 or 10W-30 (depending on the temperature range).

At a main dealer service, they put 10W-40 in it. The Opie Oils thread on here recommended 5W-40 to someone with the same car.

I'm left confused. Should I have taken issue with the dealer using a different oil from what the manufacturer state?

Since 10W/40 has almost certainly been used because it's a cheaper, more common oil, yes.

[Prawo Jazdy]

Bügger.