Using 15w40 instead of 10w30

[EMPIRE]

Unless the oil’s winter rating is so inappropriate for the starting temperature that it cannot be pumped there is no way it will be so thick as to cause an issue. And this is only a bump of one grade. It’s not going to be a problem.

It's not always about "can be pumped".
If the 5w30 and 10w30 can both be pumped on the low temp side (and meet the service category), the 5w would get going faster.

 

[kschachn]

It's not always about "can be pumped".
If the 5w30 and 10w30 can both be pumped on the low temp side (and meet the service category), the 5w would get going faster.

Pumpability is exactly what the winter rating is about. Not gelling near the pump pickup tube and causing the pump to starve.

"Get going faster"? Is that a nuclear term?

 

[EMPIRE]

Pumpability is exactly what the winter rating is about. Not gelling near the pump pickup tube and causing the pump to starve.

"Get going faster"? Is that a nuclear term?

Nope, it's Fluid Dynamics 101, although I think I did that class in HS, I think part of a "AP" class or something.

The question has nothing to do with if one will and one will not pump at those temps. They both WILL pump.

 

[kschachn]

If it can't make it to the pickup screen or tube then it won't be pumped. That's what the winter rating is for.

Hopefully this thread won't get locked like so many do.

 

[EMPIRE]

If it can't make it to the pickup screen or tube then it won't be pumped. That's what the winter rating is for.

Hopefully this thread won't get locked like so many do.

When will oil not ever be at the pickup screen or tube?
In case of OP, 5w or 10w will pump, but they will not flow the same at cold start time. Are you suggesting something other?

 

[kschachn]

When will oil not ever be at the pickup screen or tube?
In case of OP, 5w or 10w will pump, but they will not flow the same at cold start time. Are you suggesting something other?

If it is too cold and the oil gels and creates an air pocket around the pickup. This is the only place and time where flow is critical.

Do you know why ASTM D5133 is important?

 

[aquariuscsm]

I'd just use 10W30 and be done with it.

 

[Linctex]

A little 0W-20 (I have tons of this stuff from clearance sales) mixed with 15W-40 (I also have tons from clearance sales) mix together nicely for a blend that works well.

 

[ZeeOSix]

And... why does Ford "technically" call for 5w-20? Any ideas?

CAFE credits.

 

[ZeeOSix]

When will oil not ever be at the pickup screen or tube?
In case of OP, 5w or 10w will pump, but they will not flow the same at cold start time. Are you suggesting something other?

Any place oil volume is delivered via the positive displacement oil pump, as long as both oils can be pumped effectively, then the volume delivered per RPM will be the same. Obviously, if one oil is much thicker when cold the thicker oil may not flow as freely to parts that are not force fed by the PD oil pump.

 

[LeoStrop]

Don't bother to mix or complicate things up.

Use the 15W40 without worries, although the 10W30 is an excellent option as well.

 

[javacontour]

Not ideal, but in the use case as described, it will do fine.

 

[AutoMechanic]

I would not use 15W-40 oil in any type of car my dad is a truck driver and that’s the oil he uses in his truck it’s not made for cars it’s too thick for that. I’d go with a 10W-30 or 40 oil

 

[Astro14]

In an older car, and above 50F, as the OP stated, it’s fine to use the 15W40.

 

[wpod]

When will oil not ever be at the pickup screen or tube?
In case of OP, 5w or 10w will pump, but they will not flow the same at cold start time. Are you suggesting something other?

I like sucking milk vs a thick milkshake through a straw analogy.