5w20 or 5w30?

[diywannabe]

The 2010 CX-7 2.5L we just bought says 5w20 oil on the oil filler cap. It has 145,000 miles on it. Should I still use 5w30? Thanks

 

[SparkYellow]

I believe you can. The owner's manual is a bit confusing though. If you flip to page 401 of the PDF, it tells you what to use depending on where you are. 5w20 was recommended for fuel economy.

https://www.mazdausa.com/siteassets/pdf/owners-optimized/2010/cx7/2010-cx-7-owners-manual.pdf

I have a CX-3 and switched to 5w30 from 0w20.

 

[diywannabe]

I'm in Florida. It rarely gets below freezing and I've also read that in other countries Mazda recommends 5w30.

 

[Lazy2.5]

It literally makes no difference.

You can use 5w20, 5w30, whatever. Though you might even want to consider 5w40 if you're in florida, though probably not less than 5w30.

 

[N7turbo]

Highly doubt 5w40 is justified. Florida does not get hotter than Nebraska.

 

[Lazy2.5]

Highly doubt 5w40 is justified. Florida does not get hotter than Nebraska.

You can if you want to.

Or not.

Again. It doesn't make any difference. You're just going to get slightly higher oil pressures, slightly slower circulation during cold starts if it's cold out, maybe better protection when driving hard in hot weather.

I use 5w30 year-round here in Ontario. We get temps ranging from -30 to +38C at the absolute extremes.

 

[N7turbo]

Yes, because the engine is designed around 5W-30. I can't think of any reason anyone would use a 40 weight oil in these cars.

 

[Lazy2.5]

Yes, because the engine is designed around 5W-30. I can't think of any reason anyone would use a 40 weight oil in these cars.

Ok - I'll bite. Scroll down in the file attached in this post and you will find:

This is for a 2.0 CX-30. I don't care enough to find the specs for the 2.5L, but I'm sure it's the same.

So, no, this engine was not "designed around 5w30." It was designed for a wide range of oils (0W20-10W50).

 

[SparkYellow]

For BMW/MINIs where the recommended weight is 5w30, folks go up to 5w40 by the same rationale as we choose 5w30 over 0w20. I remember not noticing any difference with 5w40 on my NA R56. Folks with turbos/superchargers seemed to prefer 5w40.

 

[N7turbo]

This is for a 2.0 CX-30.

Wrong engine...

https://www.mazdausa.com/static/manuals/2023/cx-5/contents/07030402.html

 

[SparkYellow]

The OP has a 2010 CX-7 2.5. The owner's manual says use 5w20 for the 2.5 ltr engine, and 5w30 for the 2.3 ltr engine. If 5w20 is not available for the 2.5 ltr engine, then 5w30 is ok.

Good to know that newer engines can accommodate a wider range of oils.