Age old question, 5w20 vs 5w30

[M-Sport fan]

Why MTF-3? And not MTF-2?

I was just listing/mentioning them both, since some northern tier states and Canuck province members use the thinner stuff, even year round.

 

[Volumetrik]

Why MTF-3? And not MTF-2?

I decided to run MTF-3 because we get -30c temperatures a couple of times and -20c temperatures regularly during winter here in Montréal. It's thicker than the DCTF oil ford suggests, but not as thick as MTF-2.

I've had MTF-3 in my gearbox since July 2018 without issues.

 

[M-Sport fan]

I decided to run MTF-3 because we get -30c temperatures a couple of times and -20c temperatures regularly during winter here in Montréal. It's thicker than the DCTF oil ford suggests, but not as thick as MTF-2.

I've had MTF-3 in my gearbox since July 2018 without issues.

I would do the same if I lived up near/above that parallel.

Or, I would be totally, insanely OCD, and change it twice a year, by ambient temps, between the two weight MTFs.

 

[green_henry]

A 30wt oil is fine, but I’d be cautious going to a 40wt oil unless you’re absolutely sure the engine will be running hot and you have a proper oil temperature gauge.

Modern engines run tighter clearances than those of old, and the risk is that if you go out on a day where temperatures are mild and the engine is running at “normal” temperatures, you’re actually more likely to experience oil shearing (faster breakdown) and potentially oil starvation. Higher viscosity is only better until it can no longer flow where it needs to be.

Oil weights are a funny measurement as they change a lot with temperature and “W” oils are a bit misleading - for example at startup temperatures, a 0W30 is actually in between 5W20 and 5W30, because the 0W measurement only applies at something like -30C

The difference at most operating temperature from 5W20 to 5W30 is actually pretty small. Similar viscosity at about 5C higher temperature. However the jump to 5W40 is something like +25C (+45F) hotter for equivalent viscosity. So unless you really have evidence that you’re running oil 20-25C hotter at the same coolant temperatures, you’re treading in dangerous waters and 5W30 is more than enough.

https://penriteoil.com.au/knowledge-centre/Viscosity/237/what-is-an-sae-viscosity/180

A few years ago, I got distracted and accidentally bought a gallon of 5w40. I realized it before I put it in, but figured it was worth a try. It felt sluggish from the outset -- subtle but definitely noticeable -- so I went back to the store for 5w30 and changed it the same day. I considered it a flush, so didn't feel too bad about it.

 

[XR650R]

I did 5w30 for one oil change. All I noticed was about 1 mpg less, overall. I'm back on the 5w20 and mileage is same as new again.
If I lived in Tucson, I'd do the 5w30, but I don't even drive it much in the winter. I have the Winter Package EcoSport for that.
I really like it.

 

[Intuit]

Yeah I run thinner in the Winter, thicker in the Summer.
Ears "see" what the eyes cannot.
So if the valve train is noisy when hot, go thicker.
If you're getting a lot of clatter on cold start, go with the thinner stuff.
Also, don't have to go with 100% 20W or 100% 30W. You can mix weights.

 

[TyphoonFiST]

I did 5w30 for one oil change. All I noticed was about 1 mpg less, overall. I'm back on the 5w20 and mileage is same as new again.
If I lived in Tucson, I'd do the 5w30, but I don't even drive it much in the winter. I have the Winter Package EcoSport for that.
I really like it.
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