You obviously don't have a VW/Audi 1.8T!
Mixing viscosities doesn't work
- Thread starter JonS
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Of course you can mix viscosities. The results are not perfectly linear, but you will get a final fluid "inbetween" the two, not OUTSIDE. BTW-another spin on the inappropriate rock analogy is the fact that mixed-sized rocks actually make the best compacting base for road-making or driveways. I do it all the time, 1/2 pea sized and 1/2 coal-chunk sized. Packs solid and interlocks.
John_E
No I dont have a VW/Audi 1.8T, but if I did.....I wouldn't hesitate to mix 9 different types of Synthetic oils.
John_E,
Will a Redline, Amsoil, M1 & GC mix kill your engine ?? I doubt.
No I dont have a VW/Audi 1.8T, but if I did.....I wouldn't hesitate to mix 9 different types of Synthetic oils.
John_E,
Will a Redline, Amsoil, M1 & GC mix kill your engine ?? I doubt.
I've had great results mixing 10W-30 a 15W-40 Schaeffer Blends in my LS1 and 2.5L TJ.
LS1 4qts 10W-30 @ 2 1/4qts 15W-40 = 12.4cst thick 30W
TJ 3qts 10W-30 @ 2 1/4qts 15W-40 = 12.3cst thick 30W
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002310#000000
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=002245
LS1 4qts 10W-30 @ 2 1/4qts 15W-40 = 12.4cst thick 30W
TJ 3qts 10W-30 @ 2 1/4qts 15W-40 = 12.3cst thick 30W
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=3;t=002310#000000
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=002245
It should be fine when you use motor oil of the same brand with similar additive packages (by definition compatible) or of otherwise compatible oils. However - there can sometimes be undesirable effects from mixing incompatible additive packages. I understand thickening can be an issue.quote:
Originally posted by Audi Junkie:
Of course you can mix viscosities. The results are not perfectly linear, but you will get a final fluid "inbetween" the two, not OUTSIDE. BTW-another spin on the inappropriate rock analogy is the fact that mixed-sized rocks actually make the best compacting base for road-making or driveways. I do it all the time, 1/2 pea sized and 1/2 coal-chunk sized. Packs solid and interlocks.
http://groups-beta.google.com/group/rec.autos.makers.saturn/msg/4ef519443ac5b219?dmode=source
Bad analogy. First, rocks can be viewed as individual particles. You give measurements of these particles as 3 in and 2 in.
However, 10 and 30 weight are not measures of size. It is a bulk property of all the molecules in the oil mixture and how they flow. Thus, each oil separately is already a mixture of molecules. Mix the two oils together, and the bulk property will be based on the numbers of the different molecules from each oil mixed together.
Also, why couldn't you mix two oils? Using the (useful) overgeneralization of like dissolves like, nothing should stop them from mixing..........
Technically, but once they mix, they will have, together, different bulk properties that can be categorized by "weight." Without running test, we'll never know for sure in what range it would fall.....
Don't believe everything you read on the internet.....not even this!
Why would you mix viscosities in the first place? I've seen all the posts on mixing M1 10w30 and 15w50. Why? Just get the 10w40 and be happy. There so much variety of oil out there on the market. But you are going to do one better than the oil companies in the garage? Who are we kidding here.
I have a bit of Mobil 1 0w30. After the first run is complete I will get a uoa. I sincerly believe it will be just fine. If the analysis shows a need for it I will dope the next load with a little 5w40. Sometimes we end up with alot of oil and need to use it one way or another.
Short answer, the mix gives you different properties than a out of the bottle 10w-40.
I don't think they question is whether or not the base oils are "miscible". As far as I know, any reasonable amounts of PAO/ester/mineral oils will mix properly like alcohol will with water.
I think the question is:
A) What the end viscosity will be,
B) Whether the additive properties (detergency, antiwear, etc) will be ideal when mixed together,
C) Will the additives "drop out" when mixed together, and/or
D) Will the additives mixed together cause unusual effects like thickening?
My reference from the lube chemist indicated that certain mixtures of detergents could cause excessive thickening. Many oil blenders change their formulas all the time (even with the same label). I once used four bottles of Kendall 10W-30 bought on two occasions. They all had the same label (API SH) with a sticker saying they met API SJ. Two were pale and "sweet" smelling, while the other two were darker and "acrid" smelling. I just poured them in and didn't worry about it.
There's likely no cause for concern with a full oil change.
I believe that you can mix and it will do absolutly no harm, but trying to get an exact viscosity by mixing will not give you what you think you are getting.
Example: Adding Redline to get more moly.
Adding a qrt of 15w-50 M1 to thicken things up.
Example: Adding Redline to get more moly.
Adding a qrt of 15w-50 M1 to thicken things up.
Use this viscosity calculator for mixes of 2 or more motor oils and it takes the "thinking about what you are getting" out of the equation.
Click on Viscosity at this Shell Base Oils Website.
Exactly. Suppose additive packages are compatible. What if one has minimal pour point depressants while the other one relies of them for cold weather flow? What exactly is going to happen when you mix a Group III base oil w/ no VII along with a Group I base oil with lot of VI improver?
The result is likely to be something in between, but not with the kind of precision anyone is looking for. I wouldn't worry too much, because cars are rather tolerant of the viscosity of oil that goes in. My car comes with three standard recommendations for 5W-30, 10W-30, and 10W-40. Then there are desert/towing recommendations for 30, 40, 10W-50, 20W-40, or 20W-50. They have to know that someone using a car for towing isn't always going to be towing while the 20W-50 is in the crankcase.
Thanks. However - I'd just add that a 15W-40 should typically have little VII. Also - there's a question as to cold weather viscosity. The real killer probably won't be operating temp viscosity, but cold weather starts.
Triple_Se7en
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Quote:
I believe that you can mix and it will do absolutly no harm, but trying to get an exact viscosity by mixing will not give you what you think you are getting.
Examples:
Adding Redline to get more moly.
Adding a qrt of 15w-50 M1 to thicken things up.
OK then.... if the Redline has a moly number of 400.... how does it not get mixed in my engine?
How does a thicker quart of oil added to four thinner quarts not thicken what's in my crankcase?
If you had a 50-50 mixture of 20W and 40W in your engine & if you were to put a suction tube down the dipstick hole to remove 5 ounces of oil from the nearest (top) point of the crankcase .... then remove 5 ounces from the bottom of the oil pan, an oil analysis would not reveal that 20W came out the suction tube and heavier/thicker 40W oil came out the bottom of the oil pan.
Wouldn't the viscosity reading for both tests reveal the same viscosity.... meaning the two oils do mix?? Wouldn't a viscosity reading be roughly 50% in-between a virgin viscosity reading for both -- done prior to installing the two oils in your engine????????
[ May 10, 2005, 01:23 PM: Message edited by: Triple_Se7en ]
I believe that you can mix and it will do absolutly no harm, but trying to get an exact viscosity by mixing will not give you what you think you are getting.
Examples:
Adding Redline to get more moly.
Adding a qrt of 15w-50 M1 to thicken things up.
OK then.... if the Redline has a moly number of 400.... how does it not get mixed in my engine?
How does a thicker quart of oil added to four thinner quarts not thicken what's in my crankcase?
If you had a 50-50 mixture of 20W and 40W in your engine & if you were to put a suction tube down the dipstick hole to remove 5 ounces of oil from the nearest (top) point of the crankcase .... then remove 5 ounces from the bottom of the oil pan, an oil analysis would not reveal that 20W came out the suction tube and heavier/thicker 40W oil came out the bottom of the oil pan.
Wouldn't the viscosity reading for both tests reveal the same viscosity.... meaning the two oils do mix?? Wouldn't a viscosity reading be roughly 50% in-between a virgin viscosity reading for both -- done prior to installing the two oils in your engine????????
[ May 10, 2005, 01:23 PM: Message edited by: Triple_Se7en ]
Hummmm...I wonder if the "shaken not stirred" principle applies to mixing differnet viscosity oils.
So what happens to the additives in the centrifuge? Was he 'mixing' straight weight non-detergent oils? Aren't most multiweignt oils today already mixes of different base weights? The additives and VI modifiers should also form distictive layers...
Here are the results from an experiment I did a while back to see how oil transfer from hydraulic systems to engines would affect viscosity. An 8.0 cSt (100C) hydraulic oil was added to 15W40 engine oil (and vice versa) and the viscosity charted. When I have time I will repeat the experiment using two multivis oils.
I personally do not recommend mixing oils.
I personally do not recommend mixing oils.
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