Oil question: 5w40 vs 5w30

hid3

Banned
Joined
Apr 28, 2007
Location
Lithuania, Vilnius
TDI
Golf V 1.9 TDI-PD 105 HP
Hello folks.

At the moment my TDI PD has ~81k miles on it. I'm using Motul 505.01 5w40 100% syntetic oil.

My friend owns BMW 320d 100 KW with 120k miles on it and he's using 5w30 oil. He says that I'm stupid and idiot to be using 5w40 at such mileage. He claims I'd be using 5w30 instead.

I got confused. Someone told me that for our climate (West/Central Europe, in winter -25 in summer +30, humidity is high) it is a good idea to use w40.

My driving style is 95% city driving with frequent stops and accelerates.

Will it be better if I switch to 5w30 now? Guys, I need youd advice on this question, please share your opinion. Thanks.
 

Bob_Fout

Oil Wanker
Joined
Sep 5, 2004
Location
Indiana
TDI
2003 Jetta - Alaska Green (sold) / 2015 GTI 2.0T
At such mileage, LOL. 81K miles is nothing :D

You're fine. You can use either 5w30 or 5w40 that meets or exceeds 505.01.
 

wjdell

Top Post Dawg
Joined
May 17, 2006
Location
Central Florida
TDI
06 Jetta TDI DSG PKG 1 17" VV Campy White/Beige
What he probably meant was your engine is young and does not need a thick oil. That you may get better mileage or performance from a thinner oil. 12.0 vis vs 13.5. As the engine ages then thicker is less likely to pass by the rings. Oils have changed and although he may have been correct before thats not entirely correct today.
 

TornadoRed

Top Post Dawg
Joined
Aug 3, 2003
Location
West Des Moines (formerly St Paul)
TDI
2003 Jetta TDI wagon, silver; 2003 Jetta TDI wagon, indigo blue; 2003 Golf GL 5-spd, red (PARTED); 2003 Golf GLS 5-spd, indigo blue (SOLD); 2003 Jetta TDI wagon, Candy White (SOLD)
hid3 said:
Hello folks.

At the moment my TDI PD has ~81k miles on it. I'm using Motul 505.01 5w40 100% syntetic oil.

My friend owns BMW 320d 100 KW with 120k miles on it and he's using 5w30 oil. He says that I'm stupid and idiot to be using 5w40 at such mileage. He claims I'd be using 5w30 instead.

I got confused. Someone told me that for our climate (West/Central Europe, in winter -25 in summer +30, humidity is high) it is a good idea to use w40.

My driving style is 95% city driving with frequent stops and accelerates.

Will it be better if I switch to 5w30 now? Guys, I need youd advice on this question, please share your opinion. Thanks.
Some of the VW505.01-rated oils in the 5w30 viscosity range are actually very thick 30-weight oils... what might be considered a 5w38 viscosity. So there's probably not a great deal of difference between the 5w30 and 5w40.

Most TDI owners in North America are using synthetic 5w40 oils, and our conditions are just as severe as in Lithuania or the vicinity.
 

Powder Hound

Top Post Dawg
Joined
Oct 25, 1999
Location
Under a Bridge, Crestview, FL, USA
TDI
'00 Golf 4dr White 5sp, '02 Jettachero 5sp, Wife's '03 NB Platinum Gray auto(!)
Personally, I like as small a temperature range as I can get away with. Temperature ranges used to be entirely done by adding in a polymer to a thin oil. These polymers coil up at low temperatures and then lengthen out at higher temperatures. The then longer chains add viscosity at the higher temperature.

High quality oils these days have a "natural" temperature range increase as compared with older oils from, say, 20 years ago. Back then, GM did some testing and declared that a temperature range of 25 or more was a near guarantee of sludge formation in the engine due to break down and polymerization of those polymeric viscosity increasing addtives. These days, a lower quantity of those additives is required to get the temperature range, so you end up with more oil in the bottle and less additive that might sludge up your engine.

In my engine, I run a 15W-40 group V synthetic. It isn't VW approved, it just works better than anything they do approve, IMO, and that is about all anyone here can say, anyway.

My car is a Y2K vintage Golf, and so I'm not worried about 505.01 or any other VW certification. And if I was, I have 232k+ miles on it anyway, and VW will never do any powertrain warranty at this point, so what do I care what VW says?

For me, I get better mileage than nearly any gasser out there. So I look at the following: I want my car to last. My target is 500k miles. I'll do what I can to get there in one piece, and right now, I want the best protection for the engine that I can afford. That means a little thicker bottom end number than 0W or 5W. I like 15W. I'd prefer 30, really, but the manufacturer (Redline) doesn't supply a diesel formulation in viscosities other than 15W-40 AFAIK. OK, so I'll get a little lower mileage on cold winter mornings (particularly now, since I moved to NH), but I'll still be way ahead of any bimmer.

FWIW - back to flogging the dead horse (happens a lot on these threads) diesels run in a lower temperature range, have lower head temperatures, and lower heat rejection due to better thermodynamic efficiency. Sludging isn't as big a problem as it is in a gasser engine that cooks it oil at higher temps than we do. Yet another reason diesel engines last longer.
 
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