Lower Viscosty: Less Cold Engine Wear?

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They say some ungodly percentage of a car's wear comes from driving while the engine is cool.

The coolant heats up pretty quickly, but the oil is said to take much longer, and the thicker cool oil doesn't pump as well, causing limited protection against engine wear until the oil can heat up.

My car specifies something like 10W-30 oil. I am running 5W-30 PurePlus. Is it a good or bad idea to run a lower Winter viscosity? Could it help reduce the wear caused by a cold engine?
 
It depends how cold it is but everybodys engines can easily go 200k now so I dont think you should worry about reducing your startup wear IMO.
 
Originally Posted By: OpenClose
They say some ungodly percentage of a car's wear comes from driving while the engine is cool.

The coolant heats up pretty quickly, but the oil is said to take much longer, and the thicker cool oil doesn't pump as well, causing limited protection against engine wear until the oil can heat up.

My car specifies something like 10W-30 oil. I am running 5W-30 PurePlus. Is it a good or bad idea to run a lower Winter viscosity? Could it help reduce the wear caused by a cold engine?


Lots of recent posts on this subject. Check them out.

The "thicker" cold oil (your 5w or 10w) pumps just fine at 0 deg F or higher. Unless you're starting the vehicle frequently at -10 deg F or lower, the 5w is not giving you a big advantage on wear, it could be negligible. It could be said that the thicker 10w on cold start protects better until the oil flows to all components. As long as you stay above the MRV/CCS temperature pumpability limits for your 5w/10w oil, you're fine.

Check your manual again for 10w-30 vs. 5w-30. For Indiana winters most cars probably should be using 5w. Not many newer cars are spec'd for 10w anymore unless they are in warmer climates. For most days of the year, not really an issue.
 
One thing that might concern me about US oils these days is that when GF-5 was introduced, it contained for the first time, a Phosphorus Volatility spec based on the Sequence IIIG engine test. This prompted a move away from traditional light ZDDPs to heavier, less volatile ZDDPs. The idea was that heavier ZDDPs would result in less Phosphorus reaching, and poisoning, catalytic converters.

The judgement at the time was that both light and heavy ZDDPs gave equal wear prevention. However light ZDDPs are inherently more reactive, have a lower activation temperature and in theory should kick in earlier, preventing wear at lower temperatures than heavy ZDDP.

For what it's worth, my own personal opinion is that the move to heavier ZDDP's was misguided. The GF-5 limits were stupidly severe relative to real-life test data. Heavy ZDDPs added unnecessary cost to engine oils while the issue of low temperature wear was conveniently ignored.
 
Originally Posted By: OpenClose
They say some ungodly percentage of a car's wear comes from driving while the engine is cool.

The coolant heats up pretty quickly, but the oil is said to take much longer, and the thicker cool oil doesn't pump as well, causing limited protection against engine wear until the oil can heat up.

My car specifies something like 10W-30 oil. I am running 5W-30 PurePlus. Is it a good or bad idea to run a lower Winter viscosity? Could it help reduce the wear caused by a cold engine?

You've made a good choice in running a 5W-30 vs a 10W-30 for year round use in Indiana.
The car will be a little easier to start on those coldest days and a modern 5W-30 will give you all the high temperature protection you'll ever need during the hottest days of summer.
 
Originally Posted By: OpenClose
They say some ungodly percentage of a car's wear comes from driving while the engine is cool.


And how many vehicles have you seen with worn out engines because of that? The reality is that even though it may be a tiny percentage more than an "warm" start, it's not enough to waste time being concerned about it.
 
Originally Posted By: OpenClose
The coolant heats up pretty quickly, but the oil is said to take much longer, and the thicker cool oil doesn't pump as well, causing limited protection against engine wear until the oil can heat up.

My car specifies something like 10W-30 oil. I am running 5W-30 PurePlus. Is it a good or bad idea to run a lower Winter viscosity? Could it help reduce the wear caused by a cold engine?


If in fact the 10W oil was actually thicker at whatever temperature you are starting, then it would warm up quicker than a thinner oil. Plus there will be no difference in "protection".
 
Originally Posted By: surfstar
Don't worry, your engine will outlive your car. Don't fret about "engine wear". Simply stick to reasonable oil change intervals.
Seems this statement shows up in every thread. It may be true in the salt belt. It's not down here. Plenty of 20-30+ year old vehicles on the road. You need all the engine longevity you can get, especially on a truck.
 
First of all what do you define as "wear"?

Bearing pretty much last forever and it is usually the valve stem seals, cooling system, ring stuck or losing elasticity that does the engine in anyways. For these systems viscosity really doesn't make much of a difference.
 
I have been running 5w30 QSUD in my regal with no headaches at all
I do park it in the winter as the car came from Georgia and has never seen salt or snow like we have here in the Midwest

I just rolled it out for some short hops around town to get things loosened up a bit then it started to spit snow so we scrambled home.

It was quiet as a church mouse when I started it after 3 months of not running with a battery tender on it

I have a bosch 3430 filter or a PF52 on it at any given time during the summer .
 
Last edited:
Originally Posted By: 901Memphis
Supercharged 3800, try Mobil 1 0W40 or edge 0w40

Really?
The OP hasn't even said how he drives the car and you're recommending a grade heavier than specified?
 
Originally Posted By: CATERHAM
Originally Posted By: 901Memphis
Supercharged 3800, try Mobil 1 0W40 or edge 0w40

Really?
The OP hasn't even said how he drives the car and you're recommending a grade heavier than specified?


It's not uncommon for these engines to run on the warm side, around 230f coolant temps just running around town.

Not many guys have good oil temperature gauges installed but I bet it's fairly high there too.
 
Fluids don't compress so as soon as the pump starts to turn the oil is immediately pressurized no matter the weight ...As long as the ADBV is working correctly. My concern is actually the other way round. If the oil is very thin and there's just one overly worn bearing journal the pressure may not reach normal in surrounding journals as well. More so for higher mileage motors.
 
This has been done to death, and with modern motor oils, it's not really a viscosity related issue, assuming you're not choosing something unsuitable. Engine parts do change size and shape slightly upon warming. That's one issue. The big issue is that certain motor oil additives activate only with heat.

At "cold" temperatures, all oils that we have are what we'd call "too thick," in, at least, they're much thicker than what they will be at operating temperatures.
 
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