0 vs 5w20 in start stop engine

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TheKracken

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Hey everyone, so I am trying to convert my fleet to one oil grade and I am a thin oil fan.

5w20 vs 0w20 in a start stop engine: My assumption is that once the engine is up to temperature, when the engine shuts down for a minute-5 minutes the oil wont cool down enough to where the viscosity difference will be noticeable?

So I have a prius that spec's 0w20 but says 5w20 is okay just change sooner (toyota 0w is syn and 5w is not) and with the nature of the engine in a prius I was curious if 5w20 is okay? Normally I would say the start up wear would be negligible but the prius shuts the engine down and starts it back up a ton of times during any city commute.

Any opinions of the 5w20 in an engine like this? I have enough 0w20 to last me about 30k miles (1 year for me) but would like to switch to the 5w20. Let me know what you guys think.

My assumption is that once the engine is up to temperature, when the engine shuts down for a minute-5 minutes the oil wont cool down enough to where the viscosity difference will be noticeable?
 
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Won't make any difference until you're start/stopping at -40 Celsius.
Also, oils pumps are positive displacement so crankshaft rpm determines how quickly oil moves. KV numbers don't really matter.
 
Originally Posted By: Olas
Won't make any difference until you're start/stopping at -40 Celsius.
Also, oils pumps are positive displacement so crankshaft rpm determines how quickly oil moves. KV numbers don't really matter.


+1 the oil's only going to cool off a few degrees, won't make any difference.
 
A 5w-20 synthetic is no problem in the Prius.

... and if it's -40 outside, the computer wouldn't be shutting off the engine anyway, so you're good


I think they were simply trying to avoid people running conventional 5w-20 for 10k intervals.
 
My malibu has start/stop (auto stop) and ive run full syn 0w20 since it's first oil change at 4.2k. Auto stop wont engage unless the car meets certain Requirements. The oil cap says 5w20 dexos. But the owners manual says i can use 0w20 as an alternative.
 
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What I am curious about is what temperature does the oil typically run in the prius, this could tell me if there is any difference for the 0 and 5.

My prius can start auto stop feature within about a minute of starting the vehicle...I hardly believe the oil is up to temperature yet...and this is after overnight letting the car sit
 
The Prius hybrid system is WAY more complex than the Malibu. Completely different systems.

Yes, the Prius will often turn off the engine after just a minute or two, but it has nothing to do with oil temperature... its all related to the emission system.

The oil is fine and it's unaffected by the start/stop. If it's frigid, you will notice the engine stays on much longer.
 
Originally Posted By: CELICA_XX
The Prius hybrid system is WAY more complex than the Malibu. Completely different systems.

Yes, the Prius will often turn off the engine after just a minute or two, but it has nothing to do with oil temperature... its all related to the emission system.

The oil is fine and it's unaffected by the start/stop. If it's frigid, you will notice the engine stays on much longer.


So in your opinion and as a fellow gen 3 prius owner, would you think that a 5w20 synthetic will protect just as well as the
0w20 (ceterius paribus) ?

I am able to score 5w20 pennzoil ultra for a pretty decent price and after I go through all of my other oils I will be switching the entire fleet to this assuming the 5w is sufficient for the prius/
 
As others mentioned no difference at all unless you're in extremely cold climates, and then it would only matter on a cold start. If you can get PU 5w20 at a decent price go for it.
 
In Seattle or in the Yukon, the difference between 0w-20 and 5w-20 is microscopic. Your engine will not notice the difference.
 
The PNW climate is mild enough for a 10w, so 5w vs 0w will give you no difference in cold flow. Oil has a great thermal capacity and will take much longer to cool off than anything else. Changing the 5w sooner recommended under the assumption that it is not a syn oil, so forget the shortened interval.
 
In Seattle it makes no difference. In the Yukon it might. You don't see much of a difference until you get to -20F or so, in my experience.
 
Originally Posted By: WillsYoda
In Seattle it makes no difference. In the Yukon it might. You don't see much of a difference until you get to -20F or so, in my experience.


This.

In a temperate climate like Seattle, I would absolutely go with 5W-20.
 
I have used M1 0-20AFE for years and highly recommend it for all temps. It performs very well in extreme cold and high temps. My engines are very clean, use no oil in 10K OCIs, and show no sign of wear.
 
Originally Posted By: SR5
A full synthetic 5W20 should have lower noack volatility and better shear stability than an equivalent 0W20 using similar base oils.

If you don't need 0W for very cold starts -30C or below, then I would use a full synthetic 5W.



Over the life of an OCI, will this make a difference? No.

Extrapolate that to the life of the engine/vehicle. Will it make a difference? No.

The Fusion I just picked up has Start/Stop. I'm going to run M1 0w-20 AFE for the life of the vehicle.
 
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