5w30 vs 5w40 engine oil

Roberto_gas · 2023-07-25 07:40:49

I have 5w40 oil sitting which i want to use on my car which is recommended 5w30…is it ok to use 40 or it will cause issues? Also can u mix 30 and 40? Thanks in advance

25-07-2023 08:40AM

#1

Roberto_gas

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I have 5w40 oil sitting which i want to use on my car which is recommended 5w30…is it ok to use 40 or it will cause issues? Also can u mix 30 and 40?

Thanks in advance

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#2 25-07-2023 02:17PM

BlakeS94

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The only difference between the two is viscosity at engine operating temp.
The 5w40 will be thicker and won't flow as well as 5w30.
Mixing them for a top up would not cause an issue provided the oil is within manufacturer spec, that's the most important part.
But personally I wouldn't go doing a full oil change with a different viscosity oil.

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#3 25-07-2023 02:44PM

newmember2

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https://www.boards.ie/discussion/2058306333/5w30-vs-5w40-engine-oil

I think you can mix yes but it will give you a different weight oil.

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