TheSamba.com :: View topic - Anyone running 15W-40 in their beloved?

Wed Aug 09, 2006 8:50 am

[stock 1600]
I'm thinking about running Diesel 15W-40 oil all your round. Going by the weight it looks like the prefect year round oil. I'm in Socal now , but will moving to GA in a few months. I was thinking of using Rotella or Castrol GTX Diesel.

Wed Aug 09, 2006 8:54 am

may I ask WTF?

diesel oil is for diesels. not tiny little german aircooleds. I suggest you take a trip to your local motorcycle shop and buy some motorcycle oil. Its designed for aircooled engines.

Wed Aug 09, 2006 9:01 am

Rotella is fine. Diesel oils have higher detergents than gas only oils. just change every 3000 miles and enjoy your ride

Wed Aug 09, 2006 9:54 am

Man_Doun wrote: may I ask WTF?

diesel oil is for diesels. not tiny little german aircooleds. I suggest you take a trip to your local motorcycle shop and buy some motorcycle oil. Its designed for aircooled engines.

May I answer WTF? Rotella has an API SL rating which makes it completely acceptable as a gas engine oil.

http://www.shell-lubricants.com/products/pdf/RotellaTMG.pdf

Wed Aug 09, 2006 10:00 am

Man_Doun wrote: may I ask WTF?

diesel oil is for diesels. not tiny little german aircooleds. I suggest you take a trip to your local motorcycle shop and buy some motorcycle oil. Its designed for aircooled engines.

diesel oil like rotella is tough and made for pushrod engines, they even contain zinc which is found in babbit bearings.

Wed Aug 09, 2006 10:03 am

Man_Doun wrote: diesel oil is for diesels. not tiny little german aircooleds. I suggest you take a trip to your local motorcycle shop and buy some motorcycle oil. Its designed for aircooled engines.

Diesel oil is SL rated which makes it great for any aircooled engine. The added detergents & additives are fine. VW of Mexico recommends 15W40 oil in their air cooled engines & it was factory fill in the new air cooled beetles from 1992 until the end of production in 2003. For hot climates it is fine. As I'm in Northern Illinois I use 5w40 full synthetic in my Mexican beetles year 'round.

Wed Aug 09, 2006 10:15 am

I use Shell Rotella T 15W-40 in my Beetle.

Wed Aug 09, 2006 11:19 am

Sorry for the ignorance, I didn't think it would work.

Wed Aug 09, 2006 11:49 am

Yep, I use Rotella 15W-40. Runs and starts great even in cold weather.

The only reason you cannot use it in most other Gasoline vehicles is because of the zinc, it poisons the catalytic converter. But our old VW's dont have cat's so its not a problem. Zinc is GOOOD :)

I keep a 16oz. water bottle full of it for top offs, saves room from carrying a gallon jug around.

Wed Aug 09, 2006 1:02 pm

What about straight 30 weight? Will that cause probs?

Wed Aug 09, 2006 1:03 pm

CC_Hawg wrote: What about straight 30 weight? Will that cause probs?

Im running that right now, no problems

Wed Aug 09, 2006 2:16 pm

Cool - thanks!

Wed Aug 09, 2006 3:33 pm

i have a gallon jug of Shell Rotella T 15w-40 sitting around for when i get off the samba and go change my oil.... right now i have 30 weight in it.

Wed Aug 09, 2006 3:37 pm

i agree with glenn, i used shell 15-40 and never have had a problem,

Wed Aug 09, 2006 7:11 pm

Truly, straight weight oils are antique technology. Nothing wrong with them to a point but when you stop to think about the damage being done upon 1st start up with a thicker straight weight oil VS a Multi-Vis with a thinner Winter rating it doesn't make sense to use it. The same holds true with both ambient & engine temperature fluctuation.

Wed Aug 09, 2006 8:13 pm

The Rotella uses Zinc as a anti-wear additive, 30w and the vast majority of oil relies on molybdenum disulfide. As previously noted Zinc was eliiminated or greatly reduced, due to negative affect on catalytic converters. More accurate ZDDP was eliminated, which is Phosphorous and Zinc. The only thing modern 30w and older 30w (1960-70's) have in common is the weight. It not the same oil in terms of additives. When considering the VW recommended oil (30w) you need to consider the 30w now is not the same as 30w in 1970 in terms of additives and most important Zinc also Phosphorous. Standard modern gas engine oil has almost no Zinc(.05%) or Phos. the molybdenum disulfide replaced it. Older air-cooled engines need Zinc/Phos and on that basis the Rotella is better with around .14% Zinc and .12% Phos

Weight is another subject. The best weight oil for you or me depends on the climate where you live.

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Thu Aug 10, 2006 12:17 am

another vote for rotella 15/40.

Thu Aug 10, 2006 4:28 am

BUGGED11111 wrote: Older air-cooled engines need Zinc/Phos and on that basis the Rotella is better with around .14% Zinc and .12% Phos

If molybdenum disulfide has replaced zinc in modern oils and works fine with every other car on the road, why won't it work with air-cooled VWs? Not arguing, just curious.

Thu Aug 10, 2006 5:46 am

Goranothos wrote: BUGGED11111 wrote: Older air-cooled engines need Zinc/Phos and on that basis the Rotella is better with around .14% Zinc and .12% Phos

If molybdenum disulfide has replaced zinc in modern oils and works fine with every other car on the road, why won't it work with air-cooled VWs? Not arguing, just curious.

Good question. My understanding is limited to articles I've read not me having an in-depth knowledge of chemistry and metal properties.
I've read several articles and I wish I could now find all the places I've read them, but I've read enough to make me a believer. I found one which is below. I don't think this one fully answers the why question, but it's a good article. If you really want to get into the chemistry and metal properties, I think if you search the blog section of this site there is additional info. The quick answer would be type of metal in the engines in combination with the higher heat that air-cooled engines produce, makes the zinc perferred to protect parts from the effects of friction and heat on bearings,cams,etc over moly. Another article had some discussion on moly breaking down faster under repeated high heat loads and being less effective than zinc in air-cooled applications
I'll post the others articles if I can locate them.

http://www.lnengineering.com/oil.html

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Thu Aug 10, 2006 6:46 am

It is good oil for aircooled. I run Rotella Syn. 5w40 with my filtered engine and then on my '73 just plain Rotella 15-40.