Mixing different weights of oil

[sleeper]

I did a search and couldn't find anything conclusive. I know its not good to mix different makes. But is it ok to mix different weights, i.e. 5w-30 and 30wt. Thanks.

 

[chh]

From what I've read it is generally not advised to mix different weights. The mix is not 5W -30 and it is not 30w either. It would be better than running out of oil in a pinch, but I wouldn't mix it otherwise.

 

[MikePA]

It does not hurt to mix different weights or different makes.

 

[Skyco]

Not so sure it hurts but there are some oil manufacturers that advise against it even within their own oils
I asked Mobil about mixing their Delvac 1300, a mineral 15w-40, with their "synthetic" 5w-40 and they said it wasn't advised.
I had already done it in my motorcycle and the bike never shifted smoother...don't know what their exact concern was.

 

[RalphVa]

At Exxon, our lube planner would mix base stocks, 5 grade into 10 grade, 30 grade into 10 grade, etc. This is to make viscosity, flash point, boiling point, etc. on a particular base stock. It wasn't done a lot, but there certainly weren't any rules against it. We didn't go mixing huge amounts of 30 and 10 grade to made a 20 grade, for instance. Standard dino oil is a whole spread of molecules but with the average generally giving it the desired vis grade and boiling point. I've put together lube oil blending programs that mix all the properties. We had NO REASON from a research or engineering standpoint to prohibit what went into the blends, as long as the product was on spec. We generally fractionated the oils from the stills to make specifications as carefully as we could, to eliminate blending, because running more narrow cuts franctions through our dewaxing plants made them run better, and we generally didn't want to do blending in the end. However, we had no problem with doing a little end blending to make specifications.

Do not mix dino with synthetic. Otherwise, you've wasted your money that you paid extra to get the very pure synthetic. However, if it's a choice of an engine or gear box running out of oil vs. mixing, then mixing is fine.

A couple of times, I've mixed 15w50 with 5w30 to get 10w40 grade for my old Benz. Lately, I've been able to get 5w40 or 0w40; so this is what I use in it.

Ralph

 

[Soundguy]

Doesn't someone already carry a blended synthetic product.. thouhgt I had read about it somewhere.

soundguy

 

[Z-Michigan]

Several companies make synthetic blends. I have two cases of Valvoline Durablend sitting at home for my next two oil changes on the Suburban.

 

[ToadHill]

2 cases for 2 oil changes, wow, even with cases now meaning only 12 quarts thats a lot of oil for 2 changes.

 

[john_bud]

My truck is 10 qts per change.... having 2 cases isn't that much. I do 2 changes a year. Spring goes to 15w40 and fall goes to 5w40. Lucky is doesn't burn any.


jb

 

[Z-Michigan]

2 cases for 2 oil changes, wow, even with cases now meaning only 12 quarts thats a lot of oil for 2 changes.

LOL - Durablend and many synthetic oils come in cases of 6. My truck uses only 6 quarts.

Now, my other truck with a Cummins diesel does use 12 quarts or 3 gallons per oil change. But if you buy oil in gallon jugs at Wallyworld it's not too bad (still not cheap!).

 

[RalphVa]

Why not use 5w40 all year round? Even 5wxx is heavier at startup than at operating temperature. 0w40 would be even better year round and would STILL be heavier at startup than at operating temperature.

Ralph

 

[DieselPower]

Mixing different oils isn't suggested even if it's the same manufacturers oil. Different viscosity oils even from the same manufacturer and "brand" can have different additive packages. When you start mixing already blended oils your throwing out millions of dollars of research that go into blending and testing specefic oil blends. Mixing base stocks and mixing final finished blends is completly different. If your mixing base stocks here's a handy calculation tool Viscosity Index Calculation page

 

[WantedWolf]

I searched the posts, and found little bits of help, I wont mix weights for engine applications, but I should be able to mix 10w30 x 15w40 just this once for the hydraulic system, (not HS). I got some Bio stuff to replace all but I dont want to drain till I get to the shop and the hours wont be due for a month.

 

[ihookem]

I have mixed so many different oils it ain't funny. One time I mixed straight 20w with 5w30 and a qt of 10w40. Don't matter but it was an old 70 Nova.

 

[phyxer]

Well my truck holds 40 guarts (cummins M11 in a Volvo 610). As far as mixing, I'd say that as long as you mix to high quality oils then you should end up with a high quality oil....makes sense doesn't it? I normaly don't mix oils because I usually try to make sure I have spare oil around for all of my equipment. I have however been in situations in the past where I have mixed brands and weights and I have personally not noticed any ill affects to my equipment. I would personally not be afraid to do it again if need be. That's just me though, others will disagree I'm sure

Troy

 

[sandman2234]

I just changed the oil in my p/u and found that one quart of the yellow quarts was not the same as the rest. I figure it will just thin the rest out a little, but since I use a heavier oil than recommended, it probably won't hurt.
David from jax

 

[tom4018]

This topis is discussed quite a bit on the Bob is The Oil Guy website. They seem to say it is ok. There is a ton of reading over there.

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