Running 0W-40 where 5W-30 is specified

Status
Not open for further replies.
How would one know if their car's oil pump is in bypass mode,and what exactly does it mean when that happens?
 
If you have a pressure gauge, it reaches a figure then stays pegged. You can rev it cold, and see where it tops out at.

If you aren't on it continuously, then no problem...if you are, then still no problem, you are wasting energy.
 
Originally Posted By: demarpaint
Originally Posted By: CATERHAM
Originally Posted By: novadude

Can't really believe that the pump would be in bypass all the time for such a minor change in Viscosity (Remember, it's a very light 40 wt).

What you're not comparing is the more relevant HTHSVs.
M1 0W-40 is 3.85cP vs 3.1cP for M1 5W-30. That's a big difference and it is HTHSV that correlates with oil pressure which is why the oil pump will still be in by-pass mode at elevated rev's at normal operating temp's in your engine.


Does oil pump remaining in by-pass mode at elevated rpm's at normal operating temps also apply to the 2014 Coyote Ford engine [calling for 5W50] with the track pack from another thread? The reason I ask is its sister engine w/o the track pack calls for 5W20 oil. Thanks.

That's a very good point which I didn't want to get into in that thread. I'm sure it is in by-pass at normal operating temp's just like it almost certainly is with Bimmers running TWS 10W-60.
Which means the oil will likely run hotter which will further thin the oil out so that eventually it will be out of by-pass but at a higher oil temperature equilibrium.
The point being, if you're not seeing the higher oil temp's with the lighter oil it is counter-production to run anything heavier.
 
I don't really care if the pump is in bypass at high revs. I don't spend a lot of time at high revs. Besides, ALL oil pumps go into bypass at high revs, even with 0W-20.

Higher HTHS generally means higher film strength too, right? Better protecion?
 
Originally Posted By: Shannow
If you have a pressure gauge, it reaches a figure then stays pegged. You can rev it cold, and see where it tops out at.



No you can't (not on all cars). From what I've observed, the bypass restriction is going to let the pressure go higher when the oil is cold and thick and in full bypass mode. When the oil is hot and the pump is in bypass mode, the oil can pass through the restriction easier, and you see the true bypass value determined by the calibrated bypass valve spring .

I see my pressure bump close to 60 psi on the gage in my other vehicle when cold. When hot, you can rev it until it blows, and that gage will never to 45 psi.

I don't know how many millions of Chevy V8s ever survived the 1960s with no overdrive, running down the highway at 3000 rpm with pumps at the full 45 psi bypass for 1000s of miles with SF or lower API oils?

You guys are making too much of this bypass deal. Pumps run in bypass in all engines. It is not going to overheat your oil if you run the pump in bypass mode at high revs, unless we are talking about a track car. Can't see it ever being a concern on the street.

So anyway - back to the question at hand... Assuming I don't care about running a thicker oil than required, are there any real negatives to using M1 0W-40? From what I see, it's a superior oil to 5W-30 at the same price? Am I right, or am I missing something?
 
Last edited:
Originally Posted By: CATERHAM

The point being, if you're not seeing the higher oil temp's with the lighter oil it is counter-production to run anything heavier.


How do you know that? How can you tell that there is no temporary breakdown of the oil film at the piston/ring interface, etc? Maybe not enough to heat up the oil, but enough to initiate the wear process?

I am not saying go run 20W-50 in everything - I understand the benefits of thin oil (heat removal, less parasitic losses, etc, etc). However, there has GOT to be a reason why Ford, Mopar, BMW, etc all spec something heavier in their performance models that are going to take a beating.
 
Using your example 60 psi is your effective by-pass point.
The fact that the thinned out hot oil only is seeing 45 psi at high rev's is because you are operating well below by-pass.

You're asking the wrong question. If you are in by-pass at normal operating temp's running the heavier than spec' oil there are a whole lot of disadvantages. The point is, there are NO advantages.
When you say "it's a superior oil to 5W-30" what is are you referring to specifically. Higher AW and TBN levels?
You probably don't need the former and I don't thick you've expressed a desire to extend your OCI so no advantage there either.
 
My Genesis Coupe hits 75 lbs easily when the oil is cold. Then after it is warmed up it will hit 75 lbs at high rpms. If it gets to over 200F I don't think it hits the 75 lbs but the oil is seldom at that temp.
 
My car came with a sticker under the hood that says "10W is preferred" and recommends 10W30 and 10W40. Is their any advantages to me running 10W40 instead of 10W30 "wear wise" and/or vise versa?
 
Originally Posted By: SHOZ
My Genesis Coupe hits 75 lbs easily when the oil is cold. Then after it is warmed up it will hit 75 lbs at high rpms. If it gets to over 200F I don't think it hits the 75 lbs but the oil is seldom at that temp.

What oil brand and grade are you running?
 
M1 0w40.

I've run the 5w30 M1 and it will hit the 75 lbs when cold.

I should add I have a remote filter but the pressure sensor is after that.
 
Originally Posted By: aquariuscsm
My car came with a sticker under the hood that says "10W is preferred" and recommends 10W30 and 10W40. Is their any advantages to me running 10W40 instead of 10W30 "wear wise" and/or vise versa?

And 15W-40 was spec'd for '96 BMW and even heavier grades for my '86 Porsche but 5W-30 and 0W-40 have been back spec'd for both cars respectively.
GC 0W-30 or M1 0W-40 would both be superior choices to a 10W-40 for a 300ZX. Even QS Defy 5W-30 would be a good choice.
 
Originally Posted By: Shannow
If you have a pressure gauge, it reaches a figure then stays pegged. You can rev it cold, and see where it tops out at.

If you aren't on it continuously, then no problem...if you are, then still no problem, you are wasting energy.



My charger hits that at 65psi. It won't go any higher so I'm assuming that's my by-pass psi.

Originally Posted By: novadude
I don't really care if the pump is in bypass at high revs. I don't spend a lot of time at high revs. Besides, ALL oil pumps go into bypass at high revs, even with 0W-20.

Higher HTHS generally means higher film strength too, right? Better protecion?


Well not really.
If your engine only requires "x" film strength adding more doesn't mean less wear because the moving parts have an oil film separating them. A thicker oil film will add drag even if it's minutely.
However like I've already said the 0w-40 is something special. Nissan recommended it specifically for their race engines as well as Porsche and so on.
It's the only oil I'd break my boycott for to be honest,unless of course it was really cheap.
 
Originally Posted By: SHOZ
M1 0w40.

I've run the 5w30 M1 and it will hit the 75 lbs when cold.

I should add I have a remote filter but the pressure sensor is after that.

M1 0W-40 is heavier than necessary since you're not seeing high oil temp's.
I'd resume using the recommended 5W-30 grade at the next OCI.
 
That's my plan. Originally I did have oil temp problems big time. I then put on a tube and fin oil cooler that was less that stellar in performance and the adapter for it had thermostatic control at 160F. Too low when it was cool and was marginally effective when it was hot.

I've since gone to a water/oil heat exchanger on the filter mount. The radiator is way bigger than stock. I'm hoping this will take care of the heat. Most I've seen since putting that on is 215F at +90F ambient, AC on and 75 mph interstate travel. When it is cold the temp runs around 170-180F. T-stat is 180F.
 
Originally Posted By: novadude
I don't really care if the pump is in bypass at high revs. I don't spend a lot of time at high revs. Besides, ALL oil pumps go into bypass at high revs, even with 0W-20.

Higher HTHS generally means higher film strength too, right? Better protecion?

Yes even with a 0W-20 you'll need oil temp's of 65-70C before you can use maximum rev's out of by-pass.

Higher HTHSV means the oil is heavier, period even at low normal operating temp's. It's simply more accurate to refer to an oil's HTHSV rating (if you know it) than it's KV100 spec'.
 
Why would you be limiting your revs to stay out of bypass relief ?

Limiting revs because your pistons aren't round, and your block isn't straight is sensible...not bypass.
 
At least for me the coolant can be up to temp, it is the oil that takes another 10 minutes/miles.
 
Penrite has a plus 10 philosophy for vehicles in OZ see link below.

http://www.penriteoil.com.au/tech_pdfs/2...Extra%20Ten.pdf

The +10 is self explanatory. Unless you see snow I would use M1 5w-40 grade ie the same brand and additive package used by M1 5w30.

However at 147 000 miles ie approx 250 000 kms why change ?

Enough posts about switching causing leaks on this forum. The add pack in M1 0w40 I understand has much better cleaning properties, is it something you want to risk and take on at this stage of engine life ?

In summary IMO if its all good.
1. Thank God
2. Keep doing what you have been doing.
3. Switching causing leaks is not myth.
 
Last edited:
People in this forum thought they were out smarter than oil refinary and auto manufacturer by mixing their own cocktail without scientific proof. The result is unknown. But there must be a reason user manual suggests using particular weight of oil.
 
Status
Not open for further replies.
Back
Top