Just got off the phone with a Motul tech...

[dparm]

I called to inquire about which weight to run, 5w30 or 5w40. I've got a good opportunity to acquire the 300V stuff at a really low price. Explained what car I have (2005 Audi S4, 4.2L 40V V8) and that I do autocross or track it periodically.

He suggested running the 5w40, claiming that it protects like a 40 or 50 but flows like a 30. He went on to say that the 4.5 HTHS would provide excellent protection at the track. I inquired about running 5w30; he said there's nothing wrong with that since it still has HTHS of 3.6 and provides excellent shear stability.

He advised against running the 10w40 due to my location (Chicago), despite the fact the car is kept in a heated garage 6 days a week and doesn't really get parked in the cold. He did tell me that the 10w40 would be fine in the warmer months.

So in the end I am stuck wondering if the 5w30 is sufficient or if the 5w40 is going to be optimal. I run the 300V 5w40 now but their 5w40 is quite heavy (as evidenced by the 4.5 HTHS). I plan to change it in a month or two so I am also wondering if the 10w40 would be okay -- it would get changed out some time in the fall, most likely.

The car is spec'd for VW 502/505, which is heavy 30s and light 40s with HTHS of 3.5 or better.

 

[Johnny]

Well, if the car specs a heavy 30 or light 40 with an HTHS of 3.5 or better, seems the 300V 5w30 with an HTHS of 3.6 would fit the bill. I've always believed in using the thinnest oil possible to get the protection I am looking for.

I would not use the 10W-40. Just a personal opinion and preference.

 

[NateDN10]

What do you gain with 10W-40 over 5W-40?

 

[d00df00d]

Was there any suggestion that the 5w-40's chemistry might be better suited to your engine than the 5w30's?

I suspect the guy at Motul was hedging. If you were in AZ, I would agree with the suggestion for an xw-40. In IL, though, I would give the 5w30 a shot first (barring any difference in chemistry, of course).

 

[dparm]

The 10w40 is a more robust formula, I'd guess. Lower viscosity spread. The Motul tech said that if I lived in a warmer climate, he'd suggest the 10w40 in a heartbeat. No mention of any changes in additives or formulation though.

And Johnny, your reasons are exactly why I wanted to run the 5w30. It's so shear-stable that I don't really have to worry about it turning into a 20.

 

[addyguy]

Originally Posted By: NateDN10
What do you gain with 10W-40 over 5W-40?


Shear stability with less viscosity spread.

I'd take the 'safe route', and got with the 5W-40, BTW.

 

[d00df00d]

To be fair, the 5w-40 should be more than shear stable enough, as well. I would be surprised if it dropped a grade in your application.

I would pick the 5w30 because it's thinner, not because it's more shear stable.

 

[dparm]

My used oil analysis of the 5w40 (at 2500 miles, halfway to my OCI) showed very little shearing (from 13.3 to 12.4 CST, including a track day and 3 autocrosses on top of my daily lead-foot). To be fair it's the motorcycle variant but the specs are virtually identical.

 

[dparm]

The Motul tech's biggest concern for my particular car was the massive under-hood heat. It's a 4.2L V8 inside the engine bay of a Jetta, for all intensive purposes. The car has 3 radiators and a water cooled alternator. That's why he recommended the 5w40, but still said the 5w30 is quite stable in high temps and barely shears for most around-town driving.

 

[BobFout]

Nice to see you can have a good convo with tech support about oil.

 

[dparm]

Agreed. He was not a sales guy for sure. He explained the importance of the two esters, HTHS, etc. Very impressed. I guess that's the benefit of a small company, sometimes.

 

[BobFout]

Originally Posted By: dparm
Agreed. He was not a sales guy for sure. He explained the importance of the two esters, HTHS, etc. Very impressed. I guess that's the benefit of a small company, sometimes.


Motul is a small company?

 

[dparm]

Well, their US presence is small. Their US headquarters is tiny. They're no BP-Castrol...

 

[CATERHAM]

dparm, I thought you were going with Red Line 5w30?

So what's the deal on the 300V?
I'd love to try their 0W-20 but the Motul distributor up here wants
45 bucks for a two litre bottle!! I could probably beat him down to 40 bucks but that's still almost $23/L!

 

[CATERHAM]

$23/L including tax that is.

 

[d00df00d]

Originally Posted By: dparm
The Motul tech's biggest concern for my particular car was the massive under-hood heat. It's a 4.2L V8 inside the engine bay of a Jetta, for all intensive purposes. The car has 3 radiators and a water cooled alternator. That's why he recommended the 5w40, but still said the 5w30 is quite stable in high temps and barely shears for most around-town driving.

Yeah, but Audi evidently thinks that xw-30s are fine for all climates as long as they have HTHS values of 3.5 or greater and meet all the other test specs -- and you can be [censored] sure most of them aren't as tough as 300V.

 

[sangyup81]

I'm sure he would have suggested the 5w30 if you were not going to autocross or track the car or said anything about fuel economy

 

[dparm]

I have a bunch of "eBay bucks" that are going to expire. Enough to make the 300V like $10/qt...$12 after shipping (no local distributors).

 

[Audi Junkie]

I see, but I was going to say that you simply will see no benefit over the decent array of, not only otc store oils, but even conventional oils. Why not keep putting money into used oil analysis, DIY your own changes at nice short intervals with some of the great $2 oils we can buy...then you can laugh at guys overspending on oils with fancy names.

Just my opinion, you're great member here and should def do what YOU want to do, but I also think you deserve honest feedback.

You should try stuff like Mobil 1 High Mileage if you want "the best", but also I see no reason why good old Pennzoil 10w40 or HD oils would not work great.

 

[bluesubie]

Does this tech work for Motul USA? Just curious. Why not 5W-40 in spring/summer and 5w30 in fall/winter?

I'm actually thinking of running X-max 5w30. I found a good deal on-line since it's being discontinued soon.

-Dennis