2001 A6 2.7 L - Oil Change Question
#24
03-25-2009, 01:33 PM
... LOL... valid point... Colorado. Cold winter days are 10°F... coldest winter days/evenings are -10°F.
PS - I'm from ND originally, it's not THAT cold here. ...it's why I left....
PS - I'm from ND originally, it's not THAT cold here. ...it's why I left....
#25
03-25-2009, 02:21 PM
There is a situation I've been pondering upon some time.
Blends:
One blends 0W-40 and 15w-50 (equal amounts).
What the result will be:
1. an oil with 7.5w-45
2. an oil that provides range of 0w-50 protection and features.
What are your thoughts about this?
Blends:
One blends 0W-40 and 15w-50 (equal amounts).
What the result will be:
1. an oil with 7.5w-45
2. an oil that provides range of 0w-50 protection and features.
What are your thoughts about this?
#26
03-25-2009, 03:01 PM
Probably as long as both are the same brand and formulation (synthetic; non-synthetic) the symbiotic mixture would lubricate as good as any of the two individually. If you mix different brands, then you may run into incompatibilities of additives, anti-oxidants, etc.
A petrochemist would definitely offer you the "right" answer you're looking for.
However, I don't see why mixing different grades is necessary. The different oil grades are already formulated to offer the proper protection for the various climate-traffic conditions they're designed for.
If the resulting "7.5W-45" would be superior to 0W-40 and 15W-50, don't you think that the manufacturers would have already come up with such an "universal" grade?
They are actually performing tests, as compared to us, just drivers who fantasize about a new "miraculous" oil grade.
__________________________________________________ ___________________
For what is worth, here's a potential answer for you :
A petrochemist would definitely offer you the "right" answer you're looking for.
However, I don't see why mixing different grades is necessary. The different oil grades are already formulated to offer the proper protection for the various climate-traffic conditions they're designed for.
If the resulting "7.5W-45" would be superior to 0W-40 and 15W-50, don't you think that the manufacturers would have already come up with such an "universal" grade?
They are actually performing tests, as compared to us, just drivers who fantasize about a new "miraculous" oil grade.
__________________________________________________ ___________________
For what is worth, here's a potential answer for you :
All mineral oils are produced from the same basic petroleum feedstocks. Different oil viscosities will not separate or react negatively to each other because the base oil is molecularly the same. It's the different oil additive systems between brands that shouldn't be mixed - if you're concerned about the oil performing exactly how it was designed.
Oil additives include:
Anti-oxidants to prevent thickening at high operating temperatures.
Pour point depressants which lower the temperature of wax coagulation
alkaline materials to neutralize acids formed during combustion.
Rust and corrosion inhibitors.
Detergents to reduce sludge and varnish.
Dispersant additives to hold contaminants in suspension.
Extreme pressure additives to prevent metal to metal contact under high loads.
Viscosity index improvers in formulating muilt-grade (viscosity) oils.
The exact type and amount of these additives varies between brands and when mixed may not function as efficiently as desired. Different viscosities of the same brand oil will have different amounts of viscosity index improvers (polymers), but otherwise the additive systems will be the same.
From the Chevron.com site:
"Can I mix different viscosity grades of motor oils?"
"Yes. It is always advisable to not mix motor oil brands, however, different viscosity grades of the same brand motor oil are compatible. Be aware that mixing viscosity grades will turn out a product that is different in viscosity than either what was originally in the engine or what was added."
From Shell.ca:
"If you mix viscosity grades such as a 5W30 low-viscosity oil and a 10W40 higher-viscosity oil, it is reasonable to expect that the resulting product will have viscosity characteristics which are thicker than the 5W30, but thinner than the 10W40. This change does not reflect incompatibility - it's simply a re-balancing of the viscosity characteristics. In all other ways, the product should work as expected. But there's absolutely no danger about incompatibility resulting from mixing engine oils," Miller says. "We've tested all of our grades and brands, and we haven't observed any problems."
From Mobil1.com:
"For our customers to choose a viscosity grade, we recommend they follow the engine manufacturer's recommendations as indicated in their owner's manual. There is no need to mix two Mobil 1 viscosity grades when one will do; however, we see no problem mixing different SAE grades of Mobil 1 Tri-Synthetic series motor oils."
I agree that mixing oil viscosities isn't really necessary though. 5W-30 is going to have the same viscosity as 10W-30 when the oil is hot... might as well just use 5W-30 for its cold temperature "flowability". So the viscosity mixing argument is kind of pointless.
Oil additives include:
Anti-oxidants to prevent thickening at high operating temperatures.
Pour point depressants which lower the temperature of wax coagulation
alkaline materials to neutralize acids formed during combustion.
Rust and corrosion inhibitors.
Detergents to reduce sludge and varnish.
Dispersant additives to hold contaminants in suspension.
Extreme pressure additives to prevent metal to metal contact under high loads.
Viscosity index improvers in formulating muilt-grade (viscosity) oils.
The exact type and amount of these additives varies between brands and when mixed may not function as efficiently as desired. Different viscosities of the same brand oil will have different amounts of viscosity index improvers (polymers), but otherwise the additive systems will be the same.
From the Chevron.com site:
"Can I mix different viscosity grades of motor oils?"
"Yes. It is always advisable to not mix motor oil brands, however, different viscosity grades of the same brand motor oil are compatible. Be aware that mixing viscosity grades will turn out a product that is different in viscosity than either what was originally in the engine or what was added."
From Shell.ca:
"If you mix viscosity grades such as a 5W30 low-viscosity oil and a 10W40 higher-viscosity oil, it is reasonable to expect that the resulting product will have viscosity characteristics which are thicker than the 5W30, but thinner than the 10W40. This change does not reflect incompatibility - it's simply a re-balancing of the viscosity characteristics. In all other ways, the product should work as expected. But there's absolutely no danger about incompatibility resulting from mixing engine oils," Miller says. "We've tested all of our grades and brands, and we haven't observed any problems."
From Mobil1.com:
"For our customers to choose a viscosity grade, we recommend they follow the engine manufacturer's recommendations as indicated in their owner's manual. There is no need to mix two Mobil 1 viscosity grades when one will do; however, we see no problem mixing different SAE grades of Mobil 1 Tri-Synthetic series motor oils."
I agree that mixing oil viscosities isn't really necessary though. 5W-30 is going to have the same viscosity as 10W-30 when the oil is hot... might as well just use 5W-30 for its cold temperature "flowability". So the viscosity mixing argument is kind of pointless.
Last edited by chefro; 03-25-2009 at 03:04 PM.
#27
03-25-2009, 04:12 PM
Very comprehensive, indeed!
Then the result of mixing is answer 1+2 (as I always suspected).
The benefit of mixing I see is that using Mobil1 one could archive the the critical 5w-40 viscosity that is not in production!
=> mixing 0w-40 and 10w-40.
This is going to be my winning formulation at the next oil change (I believe)!
Then the result of mixing is answer 1+2 (as I always suspected).
The benefit of mixing I see is that using Mobil1 one could archive the the critical 5w-40 viscosity that is not in production!
=> mixing 0w-40 and 10w-40.
This is going to be my winning formulation at the next oil change (I believe)!
#28
03-25-2009, 04:43 PM
Interesting discussion on mixing viscosity indeed!
As going back to 6605Stang, I guess you can mix different grade to come up with your own "brew." But considering the mileage and all, I would just use 10W-40 at all times. Just warm up slowly especially during cold months.
As going back to 6605Stang, I guess you can mix different grade to come up with your own "brew." But considering the mileage and all, I would just use 10W-40 at all times. Just warm up slowly especially during cold months.
#29
03-25-2009, 04:55 PM
Good point. As anyone should do, anyway, no matter the season. Most people either don't do it, or never learned to do it.
__________________________________________________ ___________
Nemohm:
By the way, what do you mean by:
"the critical 5w-40 viscosity that is not in production!" ?
Are you talking solely about Mobil1 Synthetic for "small" cars?
__________________________________________________ ___________
Nemohm:
By the way, what do you mean by:
"the critical 5w-40 viscosity that is not in production!" ?
Are you talking solely about Mobil1 Synthetic for "small" cars?
#30
03-25-2009, 05:43 PM
Based on:
http://www.mobiloil.com/USA-English/...s/Mobil_1.aspx
what oil for "small" car is ? (Geo Metro).
Having a resulting viscosity might not be so strait forward, as the viscosity is defined by the length of the molecules.
There will be a mechanical mixture of molecules with different length, correct? Not a new averaged length molecule!
http://www.mobiloil.com/USA-English/...s/Mobil_1.aspx
what oil for "small" car is ? (Geo Metro).
Having a resulting viscosity might not be so strait forward, as the viscosity is defined by the length of the molecules.
There will be a mechanical mixture of molecules with different length, correct? Not a new averaged length molecule!
Last edited by nemohm; 03-25-2009 at 05:47 PM.