How to Reduce Viscosity of an Oil Safely

[ExMachina]

Originally Posted By: Shannow
Like I've said previously, I'm not sure that these additives behave linearly, but my interpretation of the only data that I have is that
* 10% additiion of 6cst PAO will leave you largely where you currently are
* 10% addition of 6cst PAO will dilute your AW additives by about 9%
* If you are wanting to thin your 0W40 out to 0W30, you need around 50% 0W20, and then it's (probably) thicker than a shelf bought 0W30 (and with slightly poorer cold end performance).


Great analysis! I do remember reading something about PAO that it doesn't always play nice with additives and other basestocks unless you really know what you're doing, and of course I don't.

I like the caterham-style suggestions to mix a bunch of 0w-20 in of the same brand. I'm leaning toward just throwing a pint of MMO in there on December 1 (Australian summer, U.S. winter) and let it boil off slowly through March 1 when the overnight temperatures are better. MMO thins it, right? Widman calc used. What could I possibly screw up with MMO? Ring deposits maybe? MMO is really just pale oil and mineral spirits with very little additive. I might go nuts and throw in a half cup (1/8 quart) of M1 racing 0w-30 in with the MMO just because I can..... Mad scientist, I know. I need a white lab coat and test tubes.

 

[Clevy]

Originally Posted By: MolaKule
Originally Posted By: zach1900
Drain a qt out and add the same brand of oil back in , in a 0w20-0w30 flavor.

There you go, a sensible, simple answer.



Agreed.

Unless trying to address a deposit problem I wouldn't be adding sea foam mom or any other additive just to thin the oil. That's stupidity.
And let's be realistic. A 10w is more than pump able even at -20c,and even though I'd prefer a 0w at those temps it's not like any harm is done as long as sensible warm up procedures are used.

 

[ExMachina]

Originally Posted By: Clevy
Originally Posted By: MolaKule
Originally Posted By: zach1900
Drain a qt out and add the same brand of oil back in , in a 0w20-0w30 flavor.

There you go, a sensible, simple answer.

Agreed.
Unless trying to address a deposit problem I wouldn't be adding sea foam mom or any other additive just to thin the oil. That's stupidity.
And let's be realistic. A 10w is more than pump able even at -20c,and even though I'd prefer a 0w at those temps it's not like any harm is done as long as sensible warm up procedures are used.


About pumpability, thats one thing, but pushing thick honey around at start-up doesn't get to where it should be very quickly, we have had another thread about that.
Adding MMO or SeaFoam will thin the oil, like it or not, and might as well use that fact during the winter, if no harm is done to the oil in the sump.
As for taking out a quart and putting in a quart of 0w-20, we have already established it takes a half-sump of 0w-20 to thin it out by 2 cSt kv100, not just 1 quart.

 

[ExMachina]

Looks like there was another thread years ago, and Pablo said LC20 can be used to thin. Maybe 1 oz per quart will nudge it down a little. Maybe that stuff is somehow better than MMO here.
http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/298164/1

 

[Garak]

Originally Posted By: ExMachina
About pumpability, thats one thing, but pushing thick honey around at start-up doesn't get to where it should be very quickly, we have had another thread about that.

I wouldn't worry much about a 0w-40 in the winter.

 

[Jetronic]

Originally Posted By: Shannow
Originally Posted By: ExMachina
Originally Posted By: Jetronic

add some PAO or POE ac compressor oil, the thinnest you can find.. castrol icematic sw22 has a kv40 of 22 and a kv100 of 5. not much additives either...

flashpoint is high, pour point is low, hths is a lot better than kerosene...


Adding PAO to engine oil myself. I didn't think I could get the stuff. Wow, what could adding 10% PAO hurt? Sounds like a good suggestion. Below is for Chevron Cetus PAO compressor oil:

Won't work...JMO, but I'll explain.

Mobil blender's guide for their PAO (not an M1 recipe book as some have tried to infer).

A Kg of nominal 0W40 has 341g of 4st PAO, 400g of 6 cst PAO, and 116g of VM (the nominal 0W20 is 166, 665, and 26, which I'll get to later).

Basestock on the 0W40 is 5.09cst, and 116g VII.

Replace 10% of the oil with 5.9cst PAO (assuming it's unadditised), and the new basestock is 5.16cst...thicker than you started with.

VII is reduced to 10.55% of the blend.

Honestly don't know how the curves work, but I think that you've diluted your add pack, and probably had little to no effect on viscosity which is what you want to change.

As to cutting the 40 with 20, look at the blend guide and see that the 20 has a slightly higher base oil viscosity than the 40.

Mix them 50:50, and you get
253.5g of the 4cst, 532.5g of the 6cst, and 71g of VII, which is thicker basestock than the 0W30 for similar VII treats...you'll end up thicker than the formulated 0W30 with the 50:50 blend, and poorer on the cold end than the 0W30 (thicker basestock for as give VII treat).

Like I've said previously, I'm not sure that these additives behave linearly, but my interpretation of the only data that I have is that
* 10% additiion of 6cst PAO will leave you largely where you currently are
* 10% addition of 6cst PAO will dilute your AW additives by about 9%
* If you are wanting to thin your 0W40 out to 0W30, you need around 50% 0W20, and then it's (probably) thicker than a shelf bought 0W30 (and with slightly poorer cold end performance).


Maybe you remember, likely you don't.

I mixed some POE icematic SW100 with 5w40 mineral oil and put it in the freezer + heated the mix to try to find separation. It didn't occur, so I poured the 0.2 litres of mixture in my sump, to dispose of zith the next oil change due end of august. I imagine I might have increased the viscosity of the oil at high temperatures with this mixture. There was 4.5 litres of 5w-40 oil in the sump, the level sits just above max now.

I did wonder about the what would happen with adding non-VII oil, and pretty much decided about what you stated above, but if you're mixing oil brands and thus likely VII-chemistries you don't know where you end up either... and mixing those is done at every oil change if you switch brands.