Warm up time for 0w vs 5w or 10w

[mechtech2]

Sonic -
I think it is YOU, not your wife, who needs to break the bad habits.
Start her up and drive it is best.
[This assumes you have normal oil in the crankcase.]

 

[CATERHAM]

Originally Posted By: Quattro Pete
Originally Posted By: Sonic
I ask this because if the 0w is supposed to flow a little better in the cold temps compared to a 5w it's obviously thinner at startup.

0w may be thinner than 5w but only once you get to really extreme arctic type ambient temps like below 0F. There isn't much difference between them otherwise.

That's the case with most 0w30 and 5w30 oils but not 10w30 oil which has a much lower viscosity index and therefore is still much heavier even starting on a 100F summer day.

With 20wt oils, since 0W-20s have higher VIs than 5W-20s they will be lighter on start-up at all temp's and therefore have the advantage of being closer to a more optimum viscosity at all times during the warming up process.

 

[Samilcar]

Originally Posted By: Sonic

I had a guy in a motorcycle forum tell me the exact opposite a while back. We were discussing using oil such as T6 5w40 in colder weather as compared to a 20w50. He told me to let the bike warm up longer before taking off since it starts at such a low weight.


Ask this guy if you shouldn't just use a straight 50 weight oil in the winter. According to his logic, such an oil wouldn't even need a warm up, just start it and go (this is assuming you could get the engine to even turn over to start it in the first place).

 

[s7er]

Shouldn't it be something like:
wait for a while in idle oil will heat and viscosity decreases(which is good - perfect oil viscosity around 10 cSt at 100c) and then start to move - viscosity is less and engine lubricate much better,
without waiting - viscosity is high engine lubricate much harder - bad for engine?

 

[UNC017]

Originally Posted By: Sonic
Thanks I just kept thinking that an oil that starts at 0w would take longer to get up to a 30w as compared to a 5w30 or 10w30.


You're doing what I did for years, and what most people do at first: looking at this sorta backwards. HOT is the "normal" condition for motor oil. Think of everything relative to a hot engine, and then think in terms of how much the oil thickens as it cools.

Then also remember that the WIDER the spread in rating (ie 0w30 vs 10w30) the LESS the oil changes its actual viscosity (thickness) as it cools down. So that while the 0w30 may be thinner than 5w30 when its cold, its actually about the same when its hot so it is changing thickness less than the 5w30 does. In that sense its already closer to being "up to a 30w" as you put it in the sense that a cold 0w30 is closer to the thickness of a hot SAE 30 than a cold 10w30 or 5w30 is.

Now someone will pipe up and say that, yes, there are single-grade SAE 30 oils out there that actually maintain thickness as well as a 5w30, but I'm not talking fancy ester base stock oils here.

 

[Sonic]

Hey, you guys might think I'm oblivious to motor oil but all my life I've been told to let an engine run at least 1 minute and 30 seconds before going. In fact I learned it first in auto shop back in the day, but oil and times have changed. It was to give the oil time to fully circulate through the motor before mashing the gas pedal and runnin'er straight up to 100+ (which was done many times in my buddies '79 caprice). LOL. I appreciate all the feedback on this topic.

 

[UNC017]

Originally Posted By: Sonic

I had a guy in a motorcycle forum tell me the exact opposite a while back. We were discussing using oil such as T6 5w40 in colder weather as compared to a 20w50. He told me to let the bike warm up longer before taking off since it starts at such a low weight.


That's just dead wrong. He's also looking at it backwards.

 

[Samilcar]

Sonic, sometimes it's easier to visualize something if you can see a picture. I've used the Widman oil calculator to graph the two oil grades you mentioned (Rotella T6 5W-40 and Pennzoil 20W-50):

Since the 5W-40 is much thinner at lower temperatures it requires less warm up time than the 20W-50. Don't think of "5W" and "20W" in terms of grades or weights. Those prefixes just describe how the oils behave at lower start up temperatures.

 

[Samilcar]

Originally Posted By: s7er
Shouldn't it be something like:
wait for a while in idle oil will heat and viscosity decreases(which is good - perfect oil viscosity around 10 cSt at 100c)


The problem with this is that it would take hours of idling to even approach the normal 100°C (10 cSt) oil temperature from a cold start. During those hours of idling, the oil is at sub-prime viscosity (too thick), which means MORE wear than if you had just started out driving gently (to warm up the oil as quickly as possible).

The objective for reducing start up wear is to get the oil temps as quickly as possible out of this "too thick" zone where the most wear occurs. Idling doesn't do this, gentle driving does.

 

[Gokhan]

Oil provides adequate protection even when it's very thick. In fact it provides even more protection in the boundary-lubrication regime (valvetrain etc.) when it's thick. You don't need the oil to be as thin as it's at its normal operating temperature for it to be able to provide good protection. As long as the oil can flow, you don't need to warm up an engine. This means that with a 20W-50 oil, there is no need to warm up at temperatures above freezing.

This doesn't mean that you can drive the engine hard before it reaches the normal operating temperature, even if you had 000W-10 oil in the engine. Why? Because the oil viscosity is only one of the things that change with temperature. Air - fuel ratio is very rich when the engine is cold and you would be straining the engine with too much exhaust gas if you drive it hard before it warms up. On top of that, the antiwear additives such as ZDDP and moly don't get activated until the engine warms up. You might also strain the seals etc. when you drive too hard while the oil is thick.

Bottom line: 10-second warm-up to ensure oil flow and then drive gently until it fully warms up. No need for warm-up with 20W-50 at temperatures above freezing and no need for warm-up with 5W-xx at any reasonable temperature (perhaps except in super-low temperatures in Alaska or Canada).

 

[CATERHAM]

Originally Posted By: Samilcar
Originally Posted By: s7er
Shouldn't it be something like:
wait for a while in idle oil will heat and viscosity decreases(which is good - perfect oil viscosity around 10 cSt at 100c)

The problem with this is that it would take hours of idling to even approach the normal 100°C (10 cSt) oil temperature from a cold start.

Lets not exagerate here.
An idling engine will get the oil up to normal operating temp's in about the same time as driving slowly, if not faster on a very cold day as there is no cooling air flow over the engine.
It's just a total waste of time, fuel and engine wear.

 

[Gokhan]

Originally Posted By: Samilcar
"too thick" zone where the most wear occurs

This is actually a myth. The oil doesn't cause a lot of wear because it's too thick, as long as it can flow. In fact, thick oil provides more valvetrain protection, as the valvetrain runs in the boundary-lubrication regime. Perhaps there might be more wear in a cold engine because the antiwear additives aren't activated until the engine is hot, but there won't be a lot of wear simply because the oil is thicker. You will get less fuel economy when the oil is thick but not a lot of wear. See my post above.

In any case, drive the car gently until the engine warms up, no matter what viscosity oil is used, for the reasons I explained in my post above.

 

[KrisZ]

Originally Posted By: Gokhan
Originally Posted By: Samilcar
"too thick" zone where the most wear occurs

This is actually a myth. The oil doesn't cause a lot of wear because it's too thick, as long as it can flow. In fact, thick oil provides more valvetrain protection, as the valvetrain runs in the boundary-lubrication regime. Perhaps there might be more wear in a cold engine because the antiwear additives aren't activated until the engine is hot, but there won't be a lot of wear simply because the oil is thicker. You will get less fuel economy when the oil is thick but not a lot of wear. See my post above.

In any case, drive the car gently until the engine warms up, no matter what viscosity oil is used, for the reasons I explained in my post above.


That is why automakers are pushing for 0w20 oils, it's not for cold engine protection, but for improved fuel economy. I'm still baffled about the recent 0WXX oil rage and the sudden worry of engine wear on this forum. 5W30 and 5W20 oils have been used for decades with no engine falling apart because of cold wear, so what makes everybody think that it will happen to the current engine crop?
The dexos thread is a perfect example of that. GM had a pretty clear explanation why 5w30 oil will do just fine, but that apparently was not enough for some people, because "thin is in" and GM oil choice goes against that wisdom. Toyota and Honda, on the other hand, are praised for their oil choice for some reason

.

 

[CATERHAM]

Thick oil will increase engine wear at higher rev's. The point is you don't know at what point that will occur.
Keeping the rev's down during the warming up process will obviously minimize the increased wear.
That's one of the advantages of having an oil pressure gauge.
You'll know how high you can rev the engine without the oil pump going into by pass mode. And even with a high VI 0W-20 oil you won't be able to use maximum rev's until the oil temp's are at least up to 70C and avoid going into by-pass and that can take a very long time, long after the coolant temp's have reached normal operating temp's if at all in very cold conditions.
But the lighter the oil and the higher the oil's VI the better as it will provides more of a safety margin from potential cavitation and increased wear during the warming up process.

 

[rufushusky]

Wow a lot of thought going into this thread!

My understanding something like a 5w-40, has the flow properties of a 5 weight oil at 0*C and the flow properties of a 40 weight oil at 100*C...it is not like it is an oil that is a 5 weight until a certain point and then magically a 40 weight at another.

 

[edhackett]

Remember that "start-up" wear is for the first 20 minutes of operation. That's how long it typically takes for the engine to reach full thermal stability and all operating clearances to come to their design values.

Ed

 

[Quattro Pete]

Originally Posted By: rufushusky
My understanding something like a 5w-40, has the flow properties of a 5 weight oil at 0*C and the flow properties of a 40 weight oil at 100*C...

No. The 5w number has nothing to do with 0 degrees C. The test for 5w is performed at -30 degrees C for cranking viscosity and at -35 degrees C for pumping viscosity.

http://widman.biz/English/Tables/J300.html

 

[rufushusky]

Originally Posted By: Quattro Pete
Originally Posted By: rufushusky
My understanding something like a 5w-40, has the flow properties of a 5 weight oil at 0*C and the flow properties of a 40 weight oil at 100*C...

No. The 5w number has nothing to do with 0 degrees C. The test for 5w is performed at -30 degrees C for cranking viscosity and at -35 degrees C for pumping viscosity.

http://widman.biz/English/Tables/J300.html






Hmm...learn something new every day. Thank you sir!

 

[abycat]

Originally Posted By: CATERHAM
Originally Posted By: Samilcar
Originally Posted By: s7er
Shouldn't it be something like:
wait for a while in idle oil will heat and viscosity decreases(which is good - perfect oil viscosity around 10 cSt at 100c)

The problem with this is that it would take hours of idling to even approach the normal 100°C (10 cSt) oil temperature from a cold start.

Lets not exagerate here.
An idling engine will get the oil up to normal operating temp's in about the same time as driving slowly, if not faster on a very cold day as there is no cooling air flow over the engine.
It's just a total waste of time, fuel and engine wear.


I know for sure my truck's oil temp gets up to the same temp within the same time idling or driving, from my oil pressure gauge. But i am a 5 minute idler in the summer or winter on both the vehicles. I also plug in my truck with a 400 watt block heater and a 200 watt oil pan heater.

 

[Quattro Pete]

Originally Posted By: rufushusky
Originally Posted By: Quattro Pete
Originally Posted By: rufushusky
My understanding something like a 5w-40, has the flow properties of a 5 weight oil at 0*C and the flow properties of a 40 weight oil at 100*C...

No. The 5w number has nothing to do with 0 degrees C. The test for 5w is performed at -30 degrees C for cranking viscosity and at -35 degrees C for pumping viscosity.

http://widman.biz/English/Tables/J300.html






Hmm...learn something new every day. Thank you sir!

I should have also explained that the "5" in front of the "W" is not a weight. It's a completely different nomenclature compared to the number after the "W". It's a shame SAE hasn't done a better job differentiating the two, and hence the massive confusion among consumers. They would have been better off calling it A, B, C, D instead of 0w, 5w, 10w, 15w.