I was told once by the VW experts at Gene Berg that air cooled VW engines need conventional oil rather than synthetics because "conventional oils have better heat transfer than synthetics". This sounds like slippery logic. Is it true?
Air-Cooled VW: Oils and heat transfer
- Thread starter SoxnSandals
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Can you get synthetic 50W? Not 15w50 but single grade? Bug engines are air cooled just barely.
Synthetic would be better, it can handle heat better without oxidizing/burning off in summer, and flows better in winter-as long as your engine doesn't leak it or burn it excessively. Modern oils are so much better than the oils of 1970, it's like comparing a Beetle to a Bentley.
Don't really know, but a large built German family I know had a Kombi van 1.8L?, used to tow a small Ski boat up a range after a week end skiing on the river.
They would pull up at the top of the hill and "let things cool down a bit". With a shrug of the shoulders I asked why? He said they could hear the engine oil boiling!!!
He ran M1 in it circa 1990's and the motor was still strong when he sold it 10 years later.
They would pull up at the top of the hill and "let things cool down a bit". With a shrug of the shoulders I asked why? He said they could hear the engine oil boiling!!!
He ran M1 in it circa 1990's and the motor was still strong when he sold it 10 years later.
Sorry, but this is clearly BS. Conventional and synthetic oils are both hydrocarbons with similar average molecular weights. Differences in heat capacity or heat transfer are likely to be meaningless. Here's an intersting, albeit brief paper on the topic:
http://www2.eng.cam.ac.uk/~mpfs/papers/articles/WTC2005/pdfs/t-3/WTC2005-64316.pdf
See figure 3. The differences are almost meaningless. Your VW will likely run on salad oil or Crisco; that is what they were designed for. Just change the oil every 2000 miles as the designers had envisioned, and you should be fine.
http://www2.eng.cam.ac.uk/~mpfs/papers/articles/WTC2005/pdfs/t-3/WTC2005-64316.pdf
See figure 3. The differences are almost meaningless. Your VW will likely run on salad oil or Crisco; that is what they were designed for. Just change the oil every 2000 miles as the designers had envisioned, and you should be fine.
The biggest issue with air cooled VW's is their lack of oil filtration. That means coking can create hard carbon particles that can be abrasive ... Good high temp capable synthetics (not just labeled as "synthetic") like Red Line, AmsOil signature, Motul 300V, would always be better in that engine.
But, w/o filtering, the oil must be changed often to get rid of contaminates. No one is going to toss a $30 oil fill in 3K. Better to toss a $12 oil fill with HDEO (which can also handle heat, like 1,200*F turbo temps), and do it more often. Or ...
Buy an aftermarket spin-on filter system and keep your Red Line in there for 6K
But, w/o filtering, the oil must be changed often to get rid of contaminates. No one is going to toss a $30 oil fill in 3K. Better to toss a $12 oil fill with HDEO (which can also handle heat, like 1,200*F turbo temps), and do it more often. Or ...
Buy an aftermarket spin-on filter system and keep your Red Line in there for 6K
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Lots of air cooled motorcycle engines. I always liked to use synthetic in my Ducati as recommended. Maybe Harleys use conventional as they don't put out much power, but I would still run synth.
Originally Posted By: SoxnSandals
I was told once by the VW experts at Gene Berg...
Originally Posted By: Gene Berg
We do not sell or use synthetic engine oil for the air-cooled VW as it rejects heat. The air cooled VW depends on the oil to soak up the heat from the head and carry it back to the oil cooler. With the synthetic oil the head temperature goes up and the oil temperature went down.
R.I.P. Gene Berg. Used to watch him at OCIR Bug-Ins piloting his VWs to 11-second passes!
I concur that CHT monitoring and proper thermal management are important to "air cooled" longevity.
There are, however, several methods of doing so to help ensure long and happy engine life.
Run whichever lubricants you feel appropriate then report back with your experiences. Thanks.
http://www.geneberg.com/cat.php?cPath=26_575
I was told once by the VW experts at Gene Berg...
Originally Posted By: Gene Berg
We do not sell or use synthetic engine oil for the air-cooled VW as it rejects heat. The air cooled VW depends on the oil to soak up the heat from the head and carry it back to the oil cooler. With the synthetic oil the head temperature goes up and the oil temperature went down.
R.I.P. Gene Berg. Used to watch him at OCIR Bug-Ins piloting his VWs to 11-second passes!
I concur that CHT monitoring and proper thermal management are important to "air cooled" longevity.
There are, however, several methods of doing so to help ensure long and happy engine life.
Run whichever lubricants you feel appropriate then report back with your experiences. Thanks.
http://www.geneberg.com/cat.php?cPath=26_575
Do and say what you want, but back in the day (mid 1970s) I had two bugs-a '71 and '74. Everyone I knew at the time said straight weight oil changed often.
I use 30wt in the summer and 20wt in the winter. Valvoline Racing Oil.
Never had a problem.
I use 30wt in the summer and 20wt in the winter. Valvoline Racing Oil.
Never had a problem.
Nick1994
$100 site donor 2024
I maintain my aunt’s 1970 Beetle. I have run Rotella 15w40, Mobil 1 Turbo Diesel Truck 5w40, and currently Mobil 1 HM 10w40.
Will probably switch to a 50 weight for our extreme temperatures here. Not too hot in Missippi, a 40 weight should be fine.
Will probably switch to a 50 weight for our extreme temperatures here. Not too hot in Missippi, a 40 weight should be fine.
JHZR2
Staff member
Originally Posted By: Shannow
Any difference in specific heats and convective heat transfers is going to be at the extreme end of marginal at best.
Ignore it.
+1
Any difference in specific heats and convective heat transfers is going to be at the extreme end of marginal at best.
Ignore it.
+1
I prefer synthetic in anything air cooled since they run considerably hotter than liquid cooled machines. My 400EX ATV for example, it runs around 230-250 degrees on a hot day climbing the dunes (I have an oil temp dipstick in it) whereas the average liquid cooled engine runs between 190 and 215. Makes me feel better knowing I have a stouter oil in the crankcase that won't break down as easily or burn off and leave deposits. I use Mobil 1 4t 10W-40 in that engine. I'd go for Mobil 1 15W-50 in the Bug engine if it were me. You could maybe also use 20W-50 V-twin oil? I don't think that would hurt anything, it's no different than car oil other than lack of moly to prevent wet clutch slipping.
Guys, thank you all for the comments! In 15 replies I have learned a great deal. I've learned:
There is minimal difference between conv vs syn oils regarding heat transfer. (Sorry Gene Berg, you're still the greatest)
Synthetics can withstand the higher air-cooled engine heat better
Lack of filtration demands shorter OCI
So my takeaway for my current driving style in this VW (around town, short trips) is going to be conventional with 1k to 2k OCI. If I use it for long highway trips like I used to, then synthetic is my choice.
Thanks again.
Chuck
There is minimal difference between conv vs syn oils regarding heat transfer. (Sorry Gene Berg, you're still the greatest)
Synthetics can withstand the higher air-cooled engine heat better
Lack of filtration demands shorter OCI
So my takeaway for my current driving style in this VW (around town, short trips) is going to be conventional with 1k to 2k OCI. If I use it for long highway trips like I used to, then synthetic is my choice.
Thanks again.
Chuck
It something i have read on VW forums aswell, total BS.
Originally Posted By: SoxnSandals
Guys, thank you all for the comments! In 15 replies I have learned a great deal. I've learned:
There is minimal difference between conv vs syn oils regarding heat transfer. (Sorry Gene Berg, you're still the greatest)
Synthetics can withstand the higher air-cooled engine heat better
Lack of filtration demands shorter OCI
So my takeaway for my current driving style in this VW (around town, short trips) is going to be conventional with 1k to 2k OCI. If I use it for long highway trips like I used to, then synthetic is my choice.
Thanks again.
Chuck
Synthetics don't necessarily withstand heat better as a whole than Conventional oils, there are Conventional oils like Heavy Duty engine oils which are made for diesels which are designed to withstand insane amounts of heat over very long periods of time.
The more you learn about engine oils and lubrication the more you will realise there is almost nothing that has a clear Yes/No answer.
Guys, thank you all for the comments! In 15 replies I have learned a great deal. I've learned:
There is minimal difference between conv vs syn oils regarding heat transfer. (Sorry Gene Berg, you're still the greatest)
Synthetics can withstand the higher air-cooled engine heat better
Lack of filtration demands shorter OCI
So my takeaway for my current driving style in this VW (around town, short trips) is going to be conventional with 1k to 2k OCI. If I use it for long highway trips like I used to, then synthetic is my choice.
Thanks again.
Chuck
Synthetics don't necessarily withstand heat better as a whole than Conventional oils, there are Conventional oils like Heavy Duty engine oils which are made for diesels which are designed to withstand insane amounts of heat over very long periods of time.
The more you learn about engine oils and lubrication the more you will realise there is almost nothing that has a clear Yes/No answer.
Originally Posted By: SoxnSandals
I was told once by the VW experts at Gene Berg that air cooled VW engines need conventional oil rather than synthetics because "conventional oils have better heat transfer than synthetics". This sounds like slippery logic. Is it true?
This is taken by Gospel by some in the Jeep community when it comes to gear oil. There are claims that Currie did some testing after experiencing failures in their axles and determined that synthetics were causing gear sets to run hotter so they only recommend conventional. I just don't buy it. Most trucks run synthetic in the rear axles, or require it for towing. I would think towing heavy would be the ultimate test of heat transfer.
I was told once by the VW experts at Gene Berg that air cooled VW engines need conventional oil rather than synthetics because "conventional oils have better heat transfer than synthetics". This sounds like slippery logic. Is it true?
This is taken by Gospel by some in the Jeep community when it comes to gear oil. There are claims that Currie did some testing after experiencing failures in their axles and determined that synthetics were causing gear sets to run hotter so they only recommend conventional. I just don't buy it. Most trucks run synthetic in the rear axles, or require it for towing. I would think towing heavy would be the ultimate test of heat transfer.
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