Switching grades and brands

blupupher

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So what does it mean when one runs a "frankenbrew" of multiple grades (I had a blend of 5w-20, 5w-30, 10w-30, 15w-40 and SAE 40), oil types (conventional, syn-blend and synthetic) all from different brands?

My engines rarely see the same brand oil more than one oil change, but I usually stay the same weight.
 
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Between 40C and 100C the oil viscosity changes by a factor 6... When you go to freezing temps the viscosity changes by a factor 20. When you get near the pumpability limits the oil is a hundred times as viscous then it will be hot. What difference will a few cSt make that a few thousand didn't make when you started.

it's based on a fantasy.
While viscosity does change with temperature and engines must be able to operate under a wide viscosity range, if an engine requires 0w20 the engineers certainly factored in the increase in viscosity when cold BASED off of 0w20, not 10w30/0w40 etc.

So to say that just because an engine already operates over a wide viscosity range means you can use just about any grade is false.

Also of note, some of todays 0w20's are on par with thicker oils in wear tests.
 
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I've always heard that it's not a good idea to switch between grades and brands and that you should always stick with what works. From to Scotty Kilmer to mechanics telling me my engine would have serious problems if i went from 5w40 to 10w40 because "clearances are used to 5w40" or whatever. In every car i owned i've switched between brands and grades almost every time it was due for an oil change based on what i have in my stash or what was on sale or simply out of curiosity and never had an oil leak appear or any kind of problem at all. Each time a problem such as a leak appeared is was from sitting for a long time. I don't know what this assumption is based on?
REV UP YOUR ENGINE!!!!
 
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While viscosity does change with temperature and engines must be able to operate under a wide viscosity range, if an engine requires 0w20 the engineers certainly factored in the increase in viscosity when cold BASED off of 0w20, not 10w30/0w40 etc.

So to say that just because an engine already operates over a wide viscosity range means you can use just about any grade is false.

Also of note, some of todays 0w20's are on par with thicker oils in wear tests.
No one seems to be able to say what parameters of an engine won't tolerate oils heavier than the specified 20 weights. Other than positive displacement pumps, main bearing clearances have not changed, piston to cylinder wall clearances can't get but so small, smaller with hypereutectic pistons, but those have been around before 20 wt oils.
 
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No one seems to be able to say what parameters of an engine won't tolerate oils heavier than the specified 20 weights. Other than positive displacement pumps, main bearing clearances have not changed, piston to cylinder wall clearances can't get but so small, smaller with hypereutectic pistons, but those have been around before 20 wt oils.

Is it not enough to go by what the owners manual states?
 
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Yeah I agree spasm...

It will not matter all that much 0w20 vs 10w40 or even 20w50 in motors today.

Overseas owners manuals for the same vehicle give a wide range of choices vs here.

Not that 0w20s aren't very,very good oils... They are.
 
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I can agree on that part.


In other cases it is the same cars... Exactly the same as the ones that are here and there. Like here vs Australia.

Owners manual in both places is different.
 
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While viscosity does change with temperature and engines must be able to operate under a wide viscosity range, if an engine requires 0w20 the engineers certainly factored in the increase in viscosity when cold BASED off of 0w20, not 10w30/0w40 etc.

So to say that just because an engine already operates over a wide viscosity range means you can use just about any grade is false.

Also of note, some of todays 0w20's are on par with thicker oils in wear tests.
But a 0w20 or a 0w40 will have the same viscosity at -40C....

Run the 0w20 in an engine that can't use it and the wear won't be on par. All it means is that the test engine is okay with 0W20
 
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Is it not enough to go by what the owners manual states?
Most owner manuals state a wide range actually... if you look for it

oil-chart3.png
 
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So what does it mean when one runs a "frankenbrew" of multiple grades (I had a blend of 5w-20, 5w-30, 10w-30, 15w-40 and SAE 40), oil types (conventional, syn-blend and synthetic) all from different brands?

My engines rarely see the same brand oil more than one oil change, but I usually stay the same weight.
That's not a problem. The fact is if you're draining the oil and changing the filter there isn't enough oil remaining if you leave the drain plug out for a little while to make a true Frankenbrew. ;) It's probably way less than half a quart, if that. Typically when I do an oil change on any of my three vehicles if I have a 5 quart sump I have **** near 5 quarts when I change the oil sitting in the waste oil pan. UOA shows no fuel dilution issues, so I know my fuel injectors aren't replacing oil consumed with gas.

Merry Christmas!!
 

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That's not a problem. The fact is if you're draining the oil and changing the filter there isn't enough oil remaining if you leave the drain plug out for a little while to make a true Frankenbrew. ;) It's probably way less than half a quart, if that. Typically when I do an oil change on any of my three vehicles if I have a 5 quart sump I have **** near 5 quarts when I change the oil sitting in the waste oil pan. UOA shows no fuel dilution issues, so I know my fuel injectors aren't replacing oil consumed with gas.

Merry Christmas!!
Right on … While it’s not a precise test - since there‘s trapped oil in tiny amounts all over … if you pour in a half quart with the plug out ? the odds are clean oil comes out quickly … sure has for me.

Feliz Navidad
 
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Right on … While it’s not a precise test - since there‘s trapped oil in tiny amounts all over … if you pour in a half quart with the plug out ? the odds are clean oil comes out quickly … sure has for me.

Feliz Navidad
Exactly. I've done that once or twice over the years with similar results.
 
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If you assemble a new engine and fill it with oil first time, it takes abit more. Oil you put in the filler typically goes the shortest way to the sump so isn't likely to mix with any left overs, unless what's in the sump.

It's not much leftover oil but on small diesels often enough to turn the new oil black within seconds of running.
 
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Yes I heard that it's mandated the manufacurer takes all steps necessary to ensure owners use the oil used to determine mileage.

However some still do, or specify a heavier oil for track and/or towing.

Merry Christmas to you and your family aswell!
 
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