Thick or Thin: What's more important for storage?

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So for cars that are not used that much, for instance not at all in the winter in northern climates and perhaps once a week or so during nice weather, what's more important, a thin oil, say 0w-30 or something like that which may circulate quickly; or a thicker oil like 15w-50 that might adhere to bearings and other internal parts better than thin. I don't have enough technical knowledge to know, but both arguments sound reasonable.
 
Both of the statements that you provide as "bookend" arguments aren't factual, or realistic.

Just use what's in the book. And give it a decent run when you have the opportunity.
 
I'm sure my fellow IT folks on here will get it when I say:

I was coming in here thinking this might be about network attached storage.
 
Cars will be started at 55F (in a heated garage) and up to 95F in the summer time. Cars will be driven in temps as low as 40F up to 95F
 
Originally Posted By: Building3
Cars will be started at 55F (in a heated garage) and up to 95F in the summer time. Cars will be driven in temps as low as 40F up to 95F
Thicker oil.
 
After a prolonged period of time the grade of the oil isn't going to make a bit of difference in regards to the residual film thickness. After a few hours the film thickness is down to a few microns regardless of the viscosity of the oil.
 
Oil weight will be much less a factor than making sure the system is primed before starting the engine.

I've worked it out to where I pull the appropriate fuse before storing, and then priming the engine before re-inserting said fuse before actual starting.
 
For storage the biggest issue is "drain off". It happens sometimes, mostly with synthetic oils. But, that's a very broad category in the US ...

Some oils have a lower surface tension based on the chemistry. Lower surface tension helps them attain things like 0W, etc. but it means they are less likely to maintain capillary fill. Small voids will always have a film of oil once wetted. But they can loose the thicker film cushion. Start the motor after sitting for a while (week) and they rattle until ALL the oil circulates. And since half the engine is lubed by splash and sling oil (not pumped oil), they can be quite noisy.

Good old dino oils have a mix of hydrocarbon chains by their nature. They almost always have higher surface tension and better capillary fill. They are almost always quieter on cold start after sitting.

The other issue is the filter and the anti-drain-back-valve. You want the best one you can get so that oil does not drain back into the sump. For me, that's always been WIX or Baldwin. Napa GOLD same. Use best filter you can (for construction, not necessarily efficiency).

So something like Chevron Supreme 10W-30 (easily good down to 0*F) and a Napa Gold filter means more robust residual film, quiet cold starts, and good lubrication. It's the residual oil film that has to do all the work until the oil is moving well. Sling oil off the crank is only oil that gets to cylinder walls and some cam systems.

Pumped pressure is there simply to overcome gravity for the upper end. It does not do much for a lot of the motor. So I think about residual oil film strength and film thickness over time, for seldom used vehicles (ranch trucks that only run seasonally, tractors, etc.).

If your vehicles seldom run, maybe this is the approach to take ...
 
Originally Posted By: kschachn
After a prolonged period of time the grade of the oil isn't going to make a bit of difference in regards to the residual film thickness. After a few hours the film thickness is down to a few microns regardless of the viscosity of the oil.


Bearings and pistons will still be chock a block full after years of sitting.

I've NEVER pulled apart a dry engine.
 
I don’t think it’s an issue worth spending much thought on, from a lubrication on startup perspective. It might help to have a bottle of Hy-per Lube Zinc Replacement additive in the oil since it has viscous polymer esters that are attracted to metal more so than Groups II-IV. It’s not a question of how thick are the oil films when the engine is off. Most of those thicknesses are next to zero because two or more parts have a compressive load on them, and since there is no motion, the films collapse to near zero. However, viscous esters are preferentially attracted metals more so than less polar oils, causing their concentration next to the surfaces to be higher than their concentration away from the surfaces, especially when the engine has been sitting for a long time. Because they are viscous, they help with lubrication when the engine is started up. I have no idea how much difference it would make but it only costs about $16.

Engines that sit outside and are infrequently used can have corrosion issues, albeit likely minor enough not to show up visually but enough to show up in a UOA. Some people have used oils that have additives that inhibit corrosion in the vapor phase. Some boat engine oils have these, such as Valvoline: https://www.valvoline.com/en-australia/our-products/engine-oil/valvoline-4-stroke-outboard-oil
 
Originally Posted By: Shannow
Originally Posted By: kschachn
After a prolonged period of time the grade of the oil isn't going to make a bit of difference in regards to the residual film thickness. After a few hours the film thickness is down to a few microns regardless of the viscosity of the oil.

Bearings and pistons will still be chock a block full after years of sitting.

I've NEVER pulled apart a dry engine.

Absolutely, I didn't mean for my post to imply otherwise. I tried to word it carefully as a specific response to the question title of "Thick or Thin: What's more important for storage?" I was pointing out that after a prolonged drain time the viscosity is not the determining factor in residual film thickness.
 
Originally Posted By: redhat
I'm sure my fellow IT folks on here will get it when I say:

I was coming in here thinking this might be about network attached storage.


Indeed
laugh.gif
For a few seconds I forgot this is an automotive forum and my brain immediately switched in VMWare mode (that's what I worked with recently).
 
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