Does it make any sense to mix oils?

Status
Not open for further replies.
Joined
Jun 6, 2008
Messages
1,125
Location
New Jersey
Many folks tell us they are using a mixture of two or more oils either to end up with a mid-grade that is not commercially available or to get "the best of both worlds."

I recently saw somebody say that when you mix two oils, you get something worse than either oil by itself. This makes sense to me. Who could possibly improve at home upon all the engineering that goes into a modern, advanced oil product?

Any thoughts on this?
 
MolaKule and Lubrizol have both said that mixing can have unintended consequences. One anti-wear additive could fight with another anti-wear additive and decrease the overall effectiveness, for example.

I don't foresee any catastrophic problems, but it's definitely not optimal.

Exception really is when the company says you can do it and even encourages it. Motul and Red Line both take this approach, encouraging you to mix the viscosities to get what you need.
 
its stupid, but i have done it, as my truck uses 6 quarts most oil change deals only offer 5, but as a general rule its dumb, NO ONE on here is an oil engineer as far as i know or certainly not from what ive seen
 
I only mix when im using up old stock.. the professional oil mixers know much more than me.. atleast id like to think they do
smile.gif


today i added a half a quart of Rotella T6 5-40 out of a 4 qrt jug to my silverado that calls for 5-30... watch out the sky is falling !!! the silverado was a half quart low and thats what was in the jug... fate i say fate..
 
Last edited:
Most people think you can take the mathematical average with respect to the volume of each and weight of each and the end result will tell you the final product.

While that will get you in the ballpark area of the final combined oil, it does not give you the real numbers for the final mix.
 
Originally Posted By: clarklawnscape
its stupid, but i have done it, as my truck uses 6 quarts most oil change deals only offer 5


Buy two oil change deals and use the second one over the next several changes....
 
To me...it makes sense to mix oils. I scored a load of Mobil1, PYB, Castrol GTX, Syntec synthetic, Edge, Valvoline White Bottle, Valvoline SM Red Jug MaxLife and Castrol 15w-40, Tection at Kmart clearance sales on Gallons.

I change the oil for Family, Friends, neighbors and the elderly and no oil goes to waste. The used oil and filters are disposed of properly, by bringing it back to the various Auto Shops for recycling.

For my use....Most vehicles that use oil,take more than a Gallon and some can't use heavy oils. So I'll blend the oils of different viscosity's with other....ALL IN THE SAME FAMILY....if possible to get the weight oil that I need.

Buying lots of oil, in quarts and jugs, off the clearance racks at Kmart, WM, Advance, AZ and O'Reilly has been helpful to add to some heavy grades....made by the same Family.

I have found a use for Castrol Synblend 20w-50, Castrol Edge 5w-50, Mobil 1 15w-50, Valvoline Durablend 10w-40 and 15w-40, Valvoline MaxLife 10w-40.....and so on....

I just add some of the same Brand and Type of oil in a lighter viscosity of 0w,5w-20 or 30 to get what I need.

Even Mobil 1 states, in it's frequently asked questions section....that all Mobil 1 oils are compatible with one another and can be blended or mixed with each other.

In fact I'm now running 2 different grades of Mobil 1 oils that I picked up at various Kmart store closings in Orlando, Fl. IMO...very good oil at a very good price.

In fact....I'm now about to pull the trigger on a couple of cases of Mag 1, HD Fleet Oil, 10w-30 on Amazon.

This oil should mix and blend very well with another product that I picked up at AAP, during the summer, on clearance for $1.95 a quart....Peak Full Synthetic 5w-20.

I say....mix and blend away, within the same Brand and Family, if possible.
 
Originally Posted By: TomYoung
But when someone tells you they "need" a 2.5w 28 oil, does that really reflect a need?

Of course there is no such thing as a 2.5W-28 oil.
If you mix a 0W-20 with a 5W-30 in all likelyhood you'll end up with either a heavy 5W-20 or light 5W-30.

Mixing oils can make a lot of sense but to get a good result you have to know what you're trying to acheive and that starts with knowing as much as possible about each oil, it's chemistry and PDS spec's. A example of a good blend is as follows:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2559273&page=1

All API oils by def'n must be mixable so no formulator can use an ingredient that will clash with what else is used in the marketplace. But people are cautious just the same so blending oils from the same manufacturer is a no-brainer.
For example, usually the only difference between an oil companies 5W-20 and 5W-30 grades is the amount of polymer thickeners used. In blending the two you're just varying the amount of VIIs to suit your needs. Obviously the motivation for doing so is because one thinks the 5W-20 is too light for their application or the 5W-30 is unnecessarily heavy. The only way to know for sure is the vehicle is equipped with an oil pressure gauge and possibly an oil temperature gauge as well.
 
Originally Posted By: clarklawnscape
NO ONE on here is an oil engineer as far as i know or certainly not from what ive seen


LMAO!!

I like that one. So true.

I've mixed oils that have similar add packs ie M1 0w20/0w30 but it is mostly unnecessary and me playing engineer is probably not a good thing. I don't do it anymore.
 
Originally Posted By: cp3
lol.gif


Ah, I see. So this was caused by the blend? And what would your prognosis be if the lead comes back down while I'm still using the blend?


Has your lead went back down??
 
I have yet to do another oil change, so I couldn't say. I can however see the Toromont bottle from where I sit, ready and waiting. Should be due at the end of the month.
 
Sorry to high-jack...but I thought I would share this. I have an old '86 Mazda B2000 that I purchased several months ago. Once spring hit and things warmed up I changed the oil from 10w-40 to 20w-50. The engine seem to like the thicker oil...as the valve train was quieter. Anyway...things have cooled down around here lately so I decided to switch back to a thinner oil. However, rather than going back to straight 10w-40, I mixed 2 qts of 10-40 and 2 qts of 20-50 to give a little heavier mix but still flow decent at lower temps. When I told my neighbor he said I was foolish for mixing weights. I thought that was crazy to think I was hurting something. After reading through some threads here I think I've confirmed what I already knew....I'm doing nothing wrong. So have a created a 15w-45....roughly?
 
Originally Posted By: dparm
Originally Posted By: clarklawnscape
its stupid, but i have done it, as my truck uses 6 quarts most oil change deals only offer 5


Buy two oil change deals and use the second one over the next several changes....

never thought of that, lol
 
People are just scared of the unknown. Competing AW additives for example....look at Redline!! Boat loads of Moly and Zinc and others are there a well. Maybe the right approach is to have different additives FIGHTING for various surfaces that see various conditions.

I just changed the oil in my K1500 with 2 quarts of Napa synthetic 15w50, 2 quarts of Valvoline VR1 straight 50w, and a quart of Delvac 1300 15w40. Plus two ounces of Lucas Break-In, and a can of Lubro Moly MOS2.

There, I have confessed. I am a mixing addict. I am sick. Sick.
 
Status
Not open for further replies.
Back
Top