How to Reduce Viscosity of an Oil Safely

[ExMachina]

How can an engine oil's viscosity be shifted downward, preferably without adding something that interferes with the careful balance of chemical additives already in the motor oil?

So far I've seen that SeaFoam (from their website) says you can leave it in the oil and they don't use additives, all just petroleum distillates. Sounds good. Any other options? Kerosene, diesel fuel, pure low-visc basestock (if can be bought OTC)? Kreen seems too aggressive chemically to leave in. Ditto ChemTool. Looking for something that won't bother the additives already in the motor oil. Don't want to add much, maybe half quart or so to a sump. Any suggestions?

Goal is to thin an engine oil out a couple of cP at KV100, thats all. Winter use mostly. Also to use a 40 where a 30 is spec'd.

 

[demarpaint]

Subscribed.

 

[zach1900]

Any chemical you add will interfere in some way, just by-products of combustion will, it just depends on if it's a good or bad thing!

 

[zach1900]

Drain a qt out and add the same brand of oil back in , in a 0w20-0w30 flavor.

 

[ExMachina]

Originally Posted By: zach1900
Any chemical you add will interfere in some way, just by-products of combustion will, it just depends on if it's a good or bad thing!

I'm concerned about creating more piston deposits. Guess I'd like a groupII or III basestock that has a kv100 of about 4. Additives ez to get out there that'll do this?

 

[Pontual]

I'd would use a thinner and better oil, with a better base than the original mix for the base. And very little, like 10% max. Add PAO or Ester, never a baby oil like Seafoam or MMO, unless you're trying to clean deposits, with a very short run.

 

[ExMachina]

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

Thats a go-to solution. Not sure if the additive chemistry is still compatible even in one brand. People do have good luck with mixing in 0w-20 from what I've seen.

 

[ExMachina]

Originally Posted By: Pontual
I'd would use a thinner and better oil, with a better base than the original mix for the base. And very little, like 10% max. Add PAO or Ester, never a baby oil like Seafoam or MMO, unless you're trying to clean deposits, with a very short run.


Like you, I'm leaning away from SeaFoam/MMO the more I think about it, although MMO has been around a while, hasn't seem to screw anything up over the years. Thinking maybe just straight kerosene won't clash with additives in the base oil, and its thin so I wouldn't need to put in more than a pint in a sump. Then I can calculate visc change.

 

[ExMachina]

FWIW, using the Widman visc mixing calculator, if you assume kerosene has a kv100 of 1, and you mix in a pint in a 6 quart sump of 5.5 quarts of kv100=13 oil, you get: kv100=10.3, now a 30-weight oil, so a pint is about right.

Guess thats what they recommended doing for winter in 1948 ! kerosene may be it. Better ideas?

 

[SLATRON]

I'd just add a lower grade oil of similar make up. I've done this with discount oils I've bought to adjust vis.
M1 0/40 to 0/20
Napa syn 0/20 to SM maxlife 10/40
Havo syn 0/20 to delo 5/40
Qsud 0/20 to defy 10/40
To use up spare QTS, or to use clearance oil, never a problem n normal oci

 

[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.

 

[eljefino]

Insulate your oil pan so it holds more heat when running, and use a block heater in the morning.

I'll show myself out...

 

[hansj3]

R&R the oil. Anything else may have in intended problems

 

[901Memphis]

Redline has a 4.6 cSt @100ºC synthetic race oil.

http://www.redlineoil.com/product.aspx?pid=11&pcid=1

They also have an even lighter oil they call it 2WT but the NOACK is insane and not for elevated temperatures.

 

[ExMachina]

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.


How do we know the additives in the 0w-20 don't clash with the additives in the heavier oil? Even in the same brands, we don't know what blenders are adding in.
Can you think of a straight petroleum solution, over the counter, halfway ez to get?

 

[ExMachina]

Originally Posted By: 901Memphis
Redline has a 4.6 cSt @100ºC synthetic race oil.

http://www.redlineoil.com/product.aspx?pid=11&pcid=1

They also have an even lighter oil they call it 2WT but the NOACK is insane and not for elevated temperatures.


Noticed Redline's racing oils. NOACK was off the charts for their lightest, maybe like using straight kerosene would be! The 2wt has a lot of additives in it. Trying to avoid clash of chemicals. Also, they are polyol ester basestocks I think, so not sure what effects that would be mixing with a PAO/GrpIII oil.

 

[ARCOgraphite]

I used to worry about additive clash. Valvoline Synpower LOVES a little bit of the Ifinium premium package with big boron and moly. Schaeffer does this to good effect - Look up some VOA.
I say add a good 0w20 (like PP) I had to do this to get the overly viscous 5w30 VSP DEXOS1 lube in my ROGUE into a proper operating viscosity IN THE SUMMER!
The VVT and the lightweight pistons let you know when your too thick.

Viscosity tailoring is well accepted and often necessary. See MOTUL.

Otherwise, you could add a POE refrigerant oil (ISO 32 and 68 flavours) and reap the benes of an oil that stays on the metal in a monlayer when shut off. Hopefully not varnishing

I've seen old 8oz bottles at NAPA.

 

[4D-56]

The one time that I called the makers of Kreen, I was told to add it to the oil and leave it in with confidence for the duration of a shorter (3, even 5K) OCI.

I didnt not think to ask about its effects on additives etc.

 

[ExMachina]

Actually, I found a bitog voa of MMO, and its mostly just pale oil and mineral spirits, very low on any additives per se. Found these Caterham comments about MMO (KV100=2.64), and I noticed using only 8% (pint in a 6-qt sump) bumps kv100 down by 2 cSt, the goal.

Originally Posted By: CATERHAM
With MMO's KV100 of 2.64cSt the main effect as far as I can see of adding MMO to engine oil is too reduce the viscosity.
Added to a 10cSt 30wt oil at the maximum dosage of 25% would give you a very light 20wt 7.0cSt oil.
Added to a heavy 30wt oil like GC will still reduce the viscosity to that of a 20wt 8.0cSt oil.
Added to a 40wt like M1 0W-40 would still result in a 20wt 8.6cSt oil.

What I would really like to know is what the KV40 spec' is for MMO. This would provide the viscosity index which I suspect it is quite low, in the 100 area. If I'm right, not only are you reducing the operating viscosity of the oil when you add MMO but also the oil's VI. If that's the case, one would be better off adding an ultra high VI (216) oil like the Toyota 0W-20. In so doing, you'll be reducing the operating viscosity but also increasing the oil's VI, thereby reducing the start-up viscosity disproportionately.

Using the GC example, 25% Toyota 0W-20 would still leave you with a reasonable heavy 11.1cSt, 3.3cP HTHSV 0W-30 oil but with the VI improved from 166 to about 178.

 

[chrisri]

Originally Posted By: ExMachina
FWIW, using the Widman visc mixing calculator, if you assume kerosene has a kv100 of 1, and you mix in a pint in a 6 quart sump of 5.5 quarts of kv100=13 oil, you get: kv100=10.3, now a 30-weight oil, so a pint is about right.

Guess thats what they recommended doing for winter in 1948 ! kerosene may be it. Better ideas?

What would be oil's flash point with added kerosene? I assume you've made this post for fun/academic reasons, not actually doing this in practice? Your oil of 40 grade is thinn enough.