Why can't I use 0/40 engine oil??

[skyship]

5/40 is the recommended multigrade for my Volvo diesel, but because I have to do a lot of stop start driving in winter I would like to use an 0/40 oil (Same price as a fully synthetic 5/40) for the slight improvement it provides in initial cold start wear protection terms.
I use Liqui Moly Synthoil and wrote to them asking why I should not use an 0/40 oil, but all they said was it was untested in my engine type. Volvo also say not to use 0/40 without saying why not and even some modern cars have 5/20 or 5/30 recommended and a warning not to use any zero rated oils.
Anyone know why???

 

[OpelFever]

I think it is just misinformation or CYA-mentality. Kind of like Mercedes diffs spec mineral oil and no-one recommends synthetic because it has not been officially tested and approved my MB (seal compatibility and whatever).

Peugeot and Citroen also spec 5w-40 for many older models but work just fine on 0w-40.

The Honda dealership uses Mobil Super 3000 5w-40 on new Hondas that spec 0w-20 and 0w-30, apparently they know better than the biggest engine manufacturer in the world on what oil to run in their engines. They even told a customer with a type-r that 0w-40 is "too thin" and its forbidden to use in the K-series engine.

Edit: Just had a look at the Mobil lubricants advisor and it recommends Mobil 1 0w-40 as the best option for all pre 2004 diesels. That's what we used in the quick lube I used to work at.

 

[skyship]

I did ask Liqui Moly if there was any chance of an 0/40 causing a problem with any seals and they said definitely not. The only reason I have found so far that a zero rated oil might not be as good as a 5/40, is that it might no last quite as long due the different additives required to achieve the zero rating.
In very general terms the closer the viscosity ratings of a multigrade the more shear resistant it is, but I don't know if that is the reason why some manufacturers say not to use the zero rated oils.

 

[chubbs1]

A high quality 0w oil will most likely have even better basestock's than a 5w40. That of course is a generalization but still going to be true in most cases. As OpelFever said it is the CYA thing going on. Use a 0w40 with utmost confidence, if it is going to bother you stick with 5w40. Not a big deal.

 

[ARCOgraphite]

Look for a 5w with the highest VI NOT a 0W - The 0/5/10W winter rating has nothing to do with 0 deg C and up cold start viscosity. "cheap" 0w will be less shear stable than a proper 15w/0w/15w in a diesel. You may want to look into a 30 multigrade cold climate diesel oil if worried about stop start in harsh winter conditions.

 

[Astro14]

Your Volvo is a diesel, correct? As long as the oil itself meets the applicable diesel specs for your car, then you can use it...even though a 0W40 was not among the recommended viscosities in my 2002 owner's manuals (5W40 was recommended, as was 10W30 and 5W30) I have used Mobil 1 0W40 with excellent results in my two Volvos, the key difference in my case, is that I was using it to meet a gasoline (ACEA A3/B3) specification. We don't get the D5 version over here, what is the spec that your Volvo calls for?

 

[bigjl]

Perhaps you should get in contact with Renault as your vehicle has a RenAult engine.

If you can get hold of an owners manual for the Laguna or 19 RTdt there may be a viscosity chart in it like in my wife's Clio.

It is specced for 10w40 but depending on ambient temps you can choose to use 0w40.

In fact I think you can also use a -w50 but would need to find the book to confirm.

Normally that online checkers just give the most common, one size fits all specification.

I can use a 0w40 or 5w40 but from memory even Castrol site says 10w40. That is from memory. The Mobil 1 site says 0w40 though. Why not try that one.

 

[bigjl]

Just did a check on Mobil UK site for the 1.9 engine fitted to the 19 RTdt (1870cc) it lists 0w40 as the first choice.

The Laguna 1.9 DTi 97-00 is the same 0w40

2005 onward Laguna 1.9dci is also listed as 0w40

Actually the 97-00 V40 TD is also a 0w40 as is the 16v version of the 1.9 diesel of the same years.

The Volvo v40 TD from 00-04 is also 0w40

Was writing the post whilst checking hence the length.


But from those checks I would say you are good to go according to Mobil in the UK.

 

[skyship]

Thanks for that and I just checked the Mobil oil finder and it does indeed list 0/40 turbo diesel oil. Oddly enough Mobil then list the ICI as 15K when it is in fact 20K km, although I change oil at 10K due to severe service considerations.
Volvo use Castrol Edge 5/40 in Germany and oddly enough the Castrol site also does not list the 0/40 for my Volvo or the Renault Laguna 1.9TD which has the same block, so it seems Mobil are on their own with the 0/40 recommendation.


Originally Posted By: bigjl
Just did a check on Mobil UK site for the 1.9 engine fitted to the 19 RTdt (1870cc) it lists 0w40 as the first choice.

The Laguna 1.9 DTi 97-00 is the same 0w40

2005 onward Laguna 1.9dci is also listed as 0w40

Actually the 97-00 V40 TD is also a 0w40 as is the 16v version of the 1.9 diesel of the same years.

The Volvo v40 TD from 00-04 is also 0w40

Was writing the post whilst checking hence the length.


But from those checks I would say you are good to go according to Mobil in the UK.

 

[bigjl]

Mobil recommend 0w40 New Life in lots of instances. I can't complain as that is one of the oils I can get for under £30 for five litres at local Costco. Win!

 

[syndini]

I don't understand why you don't just use what the owners manual recommends. Are the temps colder there than the temps covered in the manual?

 

[Cujet]

My guess:

Not all 0 viscosity oils have the film strength necessary to carry the high loads of diesel engines. Certainly, a "high end" 0W-40 oil would be capable of carrying high loads. But, I'd guess that the thin base oil of some 0's would be "not ideal".

Interestingly, the Duratec engines in the Jaguar X-types are prone to spinning rod bearings on the factory recommended 5W-30. The solution? Yes, you guessed it, heavier viscosity. Once again, not all 5W-30's are equal. But, clearly, the use of 10W-40 solves the problem.