Safe to mix 0W-40 and 5W-40?

[robbinthehood]

I recently had my oil change, and I believe it was filled with 5w-40. I'm looking on Amazon and the 5qt jug of 0w-40 is much cheaper than buying 5 separate quarts of 5w-40.
Would it be ok to use 0w-40 for top-offs even though it's currently filled with 5w-40?


For what it's worth, both meet the 502.00 spec:
0W-40 Link:https://www.amazon.com/Castrol-03101...&keywords=5w40
5W-40 Link: https://www.amazon.com/Castrol-06249...&keywords=5w40

If it matters, both are the Castrol Synthetic brand. I would not be mixing different brands

[L'Audi]

[Reserved for "This isn't a Civic" comment]

[Hugh@EuropaParts]

Sure... then you'll have 2.5w/40

Short answer... No.

Also, those oils are not VW/Audi approved... they just "meet spec" which is a discussion on its own.

[robbinthehood]

Sure... then you'll have 2.5w/40

Short answer... No.

Also, those oils are not VW/Audi approved... they just "meet spec" which is a discussion on its own.

Thank you for the reply. I ask because I've read elsewhere that it's ok, but I'd rather not take a chance if it's not necessary. Can you go into any more detail on it meeting spec but not being approved? Have Audi/VW specifically not approved this oil, or is it just something they haven't tested and strictly said it is approved? Am I taking too much of a chance with this oil?

[robbinthehood]

Also - now that it's full of 5w-40 castrol, would it not be safe to start using m1 0w-40 from here on out, including top-offs until my next oil change? Is it not safe to mix those either? I apologize for not knowing much about this subject, hence why I'm asking

[UberTeile]

Ummm, I do this all the time. I use M1 0W40 for my oil changes because Wally's 5qt jugs are so reasonable. But when it comes to topping up, I use Castrol Edge Professional 5W40 because it's readily available @ my work(dealership). You're not going to cause anything detrimental to occur by mixing brands/viscosity in small amounts(Audi even states this in some of their owner's manuals). You could probably even mix the 2 oils 50/50 and they would still provide adequate protection....but I wouldn't make a habit of doing that.

[robbinthehood]

Ummm, I do this all the time. I use M1 0W40 for my oil changes because Wally's 5qt jugs are so reasonable. But when it comes to topping up, I use Castrol Edge Professional 5W40 because it's readily available @ my work(dealership). You're not going to cause anything detrimental to occur by mixing brands/viscosity in small amounts(Audi even states this in some of their owner's manuals). You could probably even mix the 2 oils 50/50 and they would still provide adequate protection....but I wouldn't make a habit of doing that.

interesting...thank you for this. May get the 0w40 jug after all and save $25...

[rongeur]

I would recommend sticking with audi approved oils. See link.

https://www.audiusa.com/content/dam/...e-Bulletin.pdf

The above oil is VW 502.00 spec but not an approved oil. My guess is the discussion probably goes something like this. Approved oil are tested / licensed / approved for and by Audi and thus Audi will make it a criteria in any failure possibly oil related fault of a not approved oil. Spec just means it meets what Audi is looking for but has not been specifically tested / licensed / approved etc. This is my guess only, bobtheoilguy probably has a much better answer. For example, some people are royal purple fanatics and the 5w40 royal purple meets 502 spec but is not an approved oil as of 2015. If your engine fails and qualifies for warrenty, if Audi finds royal purple in the engine, automatic your fault for not following their approved oil list and you are on your own. However, most cars on this platform are out of their warrenty period. Many on this forum swear by Shell diesel oil as well.

To answer the question of topping off with another approved oil but slightly different weight, you should be fine. The damage done from having low oil levels far outweighs the issue of topping off with different wt but same spec oil.

[supple]

I wouldn't mix a full change worth of oil but I will top off with a different oil if I have to. Most people use Mobil 1 0W40 or Castrol Synthetic 0W40, both of which are for "European cars". I do oil changes usually with Castrol but if Mobil 1 is cheaper I do that, I keep a quart of Castrol in my trunk.

A lot of people including my roommate have always used Shell Rotella T6 which has (not sure if still true) a higher zinc content.

[robbinthehood]

I would recommend sticking with audi approved oils. See link.

https://www.audiusa.com/content/dam/...e-Bulletin.pdf

The above oil is VW 502.00 spec but not an approved oil. My guess is the discussion probably goes something like this. Approved oil are tested / licensed / approved for and by Audi and thus Audi will make it a criteria in any failure possibly oil related fault of a not approved oil. Spec just means it meets what Audi is looking for but has not been specifically tested / licensed / approved etc. This is my guess only, bobtheoilguy probably has a much better answer. For example, some people are royal purple fanatics and the 5w40 royal purple meets 502 spec but is not an approved oil as of 2015. If your engine fails and qualifies for warrenty, if Audi finds royal purple in the engine, automatic your fault for not following their approved oil list and you are on your own. However, most cars on this platform are out of their warrenty period. Many on this forum swear by Shell diesel oil as well.

To answer the question of topping off with another approved oil but slightly different weight, you should be fine. The damage done from having low oil levels far outweighs the issue of topping off with different wt but same spec oil.

Thanks for that link...the link specifically mentions the oil I linked above. Is there something I'm missing? Syntec is now called Edge, but that was nothing but a name change. Looks like both of the ones I originally linked are approved

Pasted from the link of approved oils:

Castrol Castrol Edge SAE 5W-40
Castrol Castrol Edge SAE 0W-40

VW 502 00 Castrol Castrol Syntec SAE 5W-40

[supple]

Thanks for that link...the link specifically mentions the oil I linked above. Is there something I'm missing? Syntec is now called Edge, but that was nothing but a name change. Looks like both of the ones I originally linked are approved

Pasted from the link of approved oils:

Castrol Castrol Edge SAE 5W-40
Castrol Castrol Edge SAE 0W-40

VW 502 00 Castrol Castrol Syntec SAE 5W-40

Yes it's just a name change. It's still full synth 0W40.

[robbinthehood]

Yes it's just a name change. It's still full synth 0W40.

do you agree then that it is approved by Audi? Am I missing something?

[Hugh@EuropaParts]

the fun part about oil and approvals and such is that the dealer will actually use whatever is cheaper... as they are a business... and the point of a business is to turn the highest possible profit.

Ever notice that the oil caps on many audis are stamped Castrol? Ever notice that most Castrol oils aren't VW/Audi approved?

[supple]

do you agree then that it is approved by Audi? Am I missing something?

Audi approval is as rongeur described. You can always check the back of the bottle, if it's "Audi/VW Approved" it will say VW 502 or something like that.

[robbinthehood]

the fun part about oil and approvals and such is that the dealer will actually use whatever is cheaper... as they are a business... and the point of a business is to turn the highest possible profit.

Ever notice that the oil caps on many audis are stamped Castrol? Ever notice that most Castrol oils aren't VW/Audi approved?

This audiusa pdf that was linked above specifically mentions the castrol edge
https://www.audiusa.com/content/dam/...e-Bulletin.pdf

So you are saying even though audi specifically says it meets their own spec, that it's still not approved?

- - - Updated - - -

Audi approval is as rongeur described. You can always check the back of the bottle, if it's "Audi/VW Approved" it will say VW 502 or something like that.

it does... "Meets BMW Longlife 01, Mercedes Benz 229.1 and 229.3, Porsche A40, Volkswagen 505.00 and 502.00"

I'm not sure if we are all agreeing or disagreeing that this castrol edge 5w-40 is approved by Audi.

[Theiceman]

the oils mentioned will be fine with no issues.

if it has not been Audi approved but meets spec it means the oil company hasn't written Audi a big fat cheque to endorse it.

Shell was factory Fill for years for Porsche , then overnight Mobil One became the only approved oil for all the Porsches ever built. $$$$ . I think now that agreement is up and Porsche factory fill and approved oil is something else.

[Brillo]

It is perfectly OK to top off with a premium synthetic 0W-40 if filled with synthetic 5W-40. Your engine will not know the difference and its done all the time. Back in the old days when I was racing motorcycles and Castrol did not have a synthetic oil I would regularly mix GTX with Mobil 1 cos we didn't have any money. We would beat the crap out of these bikes and occasionally tear them down for blown head gaskets and the like. They were spotless inside. We never had and wear or oil related problem. Oil manufacturers may recommend not to do this because "you will not get the full benefit of the additive package" designed into the specific oil. Baloney! I've had a Kubota diesel tractor for almost 25 years now. Kubota can't make up their mind if it should run on 15W-40 or 5W-30 so I've been running it on a 50% mix of AMSOIL for at least 15 years. It has thousands of hours on it at full throttle and still runs like a champ. Obviously this is one person's experience but it anyone has a bonafide horror story of mixing premium grade synthetic oils, let's hear about it.

[dalmation53]

I always use 5w30 full Synthetic shell rotella has been using it for the last 52k miles and car is running stronger then ever. I think is bullshit business about that Audi/Vw approved shit.

[rongeur]

FWIW, I scanned for Castrol Edge, didnt see it on the list. Didn't know Castrol renamed their oils. I dont and will never use Castrol.

[aluthman]

At the end of the day, mixing oils is worlds better than running your engine with low oil. Top off with whatever you need to as long as it isn't something like 5 year old used tractor oil. As long as you do reasonably timed oil changes, your car probably won't give two shits.

[robbinthehood]

FWIW, I scanned for Castrol Edge, didnt see it on the list. Didn't know Castrol renamed their oils. I dont and will never use Castrol.

It's in alphabetical order, do a Ctrl+F and search for castrol. I copied and pasted it directly from the list

[dalmation53]

At the end of the day, mixing oils is worlds better than running your engine with low oil. Top off with whatever you need to as long as it isn't something like 5 year old used tractor oil. As long as you do reasonably timed oil changes, your car probably won't give two shits.

hahaha yeah the car won't even notice. but in all seriousness like i said is all business. I always run 5w30 full syn. and sometimes buy 5w40 quart on special and car doesn't mind that at all.

[Luis_Heineken]

I always use 5w30 full Synthetic shell rotella has been using it for the last 52k miles and car is running stronger then ever. I think is bullshit business about that Audi/Vw approved shit.

5w30?

Not 5w40?

[dalmation53]

5w30?

Not 5w40?

Yes 5w30 full syn. For some reason the 5w40 doesn't last and then i switched to 5w30 and idle feel smoother and it last longer. Maybe the car was running with that since new. I guess it got used to it.


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[aluthman]

I broke my engine in on non-detergent SAE 30 conventional oil and it didn't blow up. The slight differences on weight of synthetic oil mentioned in this thread will not cause a problem.

[Obsidian]

Shell Rotella T6 5w40... Always on sale somewhere and smooth as butter. I have been using it with no issues.

[aluthman]

^^ I'm currently running T6 Rotella 5w-40 and have not burned a drop in 2500 miles on my new engine.

[keaton85]

+1 on T6

It's excellent because I can have it for the TDIs in the family as well. Cheap and pretty universal in my opinion...

[wding2000]

Audi Technical Bulletin: Mobil 1 5W40, Castro Edge 5W40 all meet Audi standard.
https://www.audiusa.com/content/dam/...e-Bulletin.pdf