Mixed Oil Debate

All joking aside. I have a mixture of 2 quarts of Valvoline synthetic 0/20 and 2 quarts of Valvoline synthetic 5/30 that were leftovers from some OCs on friends vehicles over the last few months. I deemed them too valuable to throw in the Frankenoil jug.

I have zero qualms about using this mixture in my wife's Corolla's upcoming OC.
 
ka9mnx said:
If you have left over oil after an OCI, you bought too much. If you have left over oil, put it in you lawn mower.
Click to expand...
I don't have oil left over from a single oil change. When I've bought oil in the past I buy several cases at a time. Over 50-100K miles I may have to add oil on occasion therefore it's hard to know exactly how many oil changes I'm going to get out of 5-10 cases of oil. I use straight 30w in my my lawn mowers instead of multi viscosity.
 
stower17 said:
That quote you posted literally confirms what I said in that there is no harm in mixing.
Click to expand...
OK, lets turn that around.

What is the benefit to mixing?

I would like to see one verifiable legitimate example where any mixing of any oil provided any legitimate benefit that would be unattainable by any properly spec'd oil right out of the bottle.

Anybody have one?

Otherwise, I write the effort off as an ignorant persons exercise in vanity if they do it thinking they have actually achieved something.
 
ABN_CBT_ENGR said:
OK, lets turn that around.

What is the benefit to mixing?
Click to expand...

Me: Honey, I need to buy some oil.
Her: Why?
Me: Because I need to change the oil in your car.
Her: Why?
Me: Umm...'cause it's due
Her: But why now?
Me: Because it is.
Her: We don't need to spend money on oil right now.
Me: But you just paid $30 for a bottle of shampoo.
Her: That's different. I needed that.

Alternatively:

Me: Honey, I'm changing the oil in your car. But I don't have to buy any oil because I already have some.
Her: Ok
 
Hogwash said:
Me: Honey, I need to buy some oil.
Her: Why?
Me: Because I need to change the oil in your car.
Her: Why?
Me: Umm...'cause it's due
Her: But why now?
Me: Because it is.
Her: We don't need to spend money on oil right now.
Me: But you just paid $30 for a bottle of shampoo.
Her: That's different. I needed that.

Alternatively:

Me: Honey, I'm changing the oil in your car. But I don't have to buy any oil because I already have some.
Her: Ok
Click to expand...
I stand corrected

What is the benefit IN MECHANICAL TERMS TO THE ENGINE ?
 
Yes it's OK once in a while, just don't make it a habit. Maybe it would be better to say that I recommend using the same brand and grade of oil as consistently as possible, when you are able, but don't hesitate to add part of a different brand or grade if you need to top up or use some leftover stash. As long as it meets the spec of the vehicle.
I understand that the API or some other agency requires that motor oils have some level of compatibility but I'm not sure on the language they use... just keep in mind it's what I heard from my mechanic's barber's cousin's postman's doctor.
 
Hogwash said:
Me: Honey, I need to buy some oil.
Her: Why?
Me: Because I need to change the oil in your car.
Her: Why?
Me: Umm...'cause it's due
Her: But why now?
Me: Because it is.
Her: We don't need to spend money on oil right now.
Me: But you just paid $30 for a bottle of shampoo.
Her: That's different. I needed that.

Alternatively:

Me: Honey, I'm changing the oil in your car. But I don't have to buy any oil because I already have some.
Her: Ok
Click to expand...

lol @ shampoo

I just tell the wife I'm saving us a bunch of money by doing it myself
 
alcyon said:
Mix if you have to just to use up old stuff, but not on purpose on every oil change.
Click to expand...
Why is it OK if you want to use up old stuff, but not OK to do it with new oil ... ex: mixing 0W-20 with 5W-30 of the same brand and flavor, Castrol EP or Mobil 1 EP? It seems to me that using similarly formulated oils would be the ideal way to go if one wanted to mix. Why not every oil change under such a circumstance? Perhaps not ideal, but maybe most ideal?
 
No do not mix. Stick to the most expensive one you can find. (sarcasm)

Leave the sales and rebates and the walmart mis-pricing for the rest of us. 🤣
 
stower17 said:
We don’t know what the reference oils are. If we do then I’ve never seen it. They could be specifically blended oils that are designed to cause negative effects when tested with sample oils with incompatible elements.

The OEM’s obviously care if motor oils are compatible with each other. I would imagine that warranty costs would skyrocket if oils weren’t compatible with each other and we would surely see disclaimers in owner’s manuals saying not to mix brands. What we have with the API is a collaborative effort between OEM’s, oil formulators, and oil marketers, and there is clearly a vested interest with all parties involved that all the products don’t cause undue harm to another competitors product.

If you are using the correct oil specification for your engine, using different brands simultaneously should be of no worry. If using a non API rated oil or OTC additives then all bets are off. After being here for 10 years I can’t believe how so many old myths still get circulated.
Click to expand...

What part exactly is a myth?

As I clearly outlined, multiple times now, the purpose of the test is to determine with a relatively degree of certainty based on the outcomes of mixing with the test oils, that there aren't going to be dramatic negative synergies.

Everything you've posited is covered in that statement.

In the event that oils are mixed, the most typical event being that somebody tops up with another brand, the odds are extremely low that a significant negative interaction would take place, that is the purpose of the test in its entirety.

Joe Average doesn't go around mixing 20 different oils together thinking he's playing chemist and that this is somehow endorsed by the API miscibility standard. It clearly isn't, the standard does not in any way guarantee anything beyond what it tests for, full stop.

Since most users aren't doing the above, and most vehicles under warranty are serviced at the dealer or Jiffy Lube, the idea that this would somehow have an impact on warranty claims is ridiculous. Most people don't change their own oil, hell, most people don't even check their oil.
 
Mobil doesn't recommend mixing BTW:
Screen Shot 2020-12-08 at 11.07.55 PM.png


Note the verbiage, IN GENERAL, SHOULD be compatible, NOT LIKELY that you would get a gel. They do NOT recommend mixing oils as a general practice for many of the reasons I've already outlined.

This is all in-line with the miscibility standard.

AMSOIL also doesn't recommend it:
Screen Shot 2020-12-08 at 11.19.04 PM.png


Royal Purple:
Screen Shot 2020-12-08 at 11.40.32 PM.png


So, can you, if necessary, with minimal risk? Yes. Should you? No.


Somewhat OT, it's funny seeing aviation piston engine oil call-outs on mixing, since there isn't a miscibility standard in play, such as this one from Lycoming:
The latest revision to Lycoming Service Instruction 1014 gives recommendations for lubricating oils, oil change intervals and engine break-in. Pilots and mechanics should know what weight, type and brand of oil is being used in the engine being serviced. At each oil change, this specific information should be recorded in the engine logbook. Except as a temporary measure in an emergency, different oils should not be mixed. Consistent indiscriminate mixing of oils may create high oil-consumption problems or clogged oil control rings and oil screens.
Click to expand...
 
You must log in or register to reply here.

Similar threads

9
Castrol Edge 5w-50
Replies
4
Views
752
99Saturn
S
Mobil1 EP 0W-20 vs Total Quartz 9000 XTRA Future FGC
Replies
8
Views
654
kschachn
T
Oil Seal Life vs Oil Grade Study
Replies
4
Views
1K
nobb
I
Time to switch oils in 2007 Subaru EJ25 turbo with 150k?
2 3
Replies
44
Views
4K
Impatient
Alien
  • Article
Mobil 1 Classic 0W30: best cold weather oil?
4 5 6
Replies
114
Views
7K
Yolo
Back
Top