Oil for Aircooled Engines

[Bill888]

I was checking the data posted by 1FMF. I have a 66 Porsche 912 that I've used 20/50 GTX in for quite a number of years. Since these (and VW's and 911) motors are pretty much air&oil cooled, my question is:
Is there any data which shows an oil's ability to dissipate heat (i.e. in the cooler?) Are synthetics better at this and/or is there an optimum viscosity when hot?
Over the years I've met other airheads who swear by straight 30 Castrol HD; 20/50GTX and then those who run true synthetics and claim lower max operating temps. This all applies to SoCal where winter cold starts are not an issue.
All opinions/experiences appreciated.
Bill.

 

[castor]

hi bill.
for what it's worth, i've just started using the appropriate grade diesil oil in my harley. i assume most motorcycles are like your porsche, ie redlined, run hot(todays gas?) and not used as frequently as cars.
my cycle seems to run rather well on this heavy duty oil. it is a VERY cost effective lube and can be found anywhere
btw, i lavish love and attention my bike, bought it new in '92 and it still looks near brand new

 

[Quest]

Just go with HDEO (15W40 typical) and you'll be fine.

No need to go with exotic synthetics. Just heavy duty diesel truck oil shall do.

 

[Bob Woods]

My last aircooled VW was a 79 camper bus with 2L pancake engine,(same engine as Porsche 914-4) during the summer it would use a quart per 1000 mile until I switched to MobilOne, then oil consumpion ceased. Using diesel rated oil in a spark ignited engine is wasteing the additive package.

 

[castor]

clarification bob, the oil i use is DUAL rated

 

[CBDFrontier06]

I ran Castrol 20W-50 in my 74 Beetle, and it burned less of that than anything else I tried....and was also the only oil that kept highway engine temps below 230 F.

 

[ewetho]

For what it is worth Gene Berg of air cooled VW fame recommends Dino for use in air cooled motors for better heat ransfer. Now his data is several years old at this time but they did extensive research monitoring temps in all parts of the motor and post teardown analysis and found it is best. As for brand pick your favorite.

But then there are lots of Porches that ran Mobil1 very successfully so who know. Just and interesting side point I guess.

 

[CBDFrontier06]

I chose dino for my Beetle just to avoid developing any seal leaks....but if I'd rebuilt it or bought a new engine, I'd have run synthetic for it's better thermal protection. Poor thing ran very hot on the highway, but strangely kept its cool in stop-and-go in Dallas.

 

[Eddie]

What does the Factory recomend? and what is the factory load as new? I thought it was Mobil 1 5w or 0w40?

 

[vronline]

It's a '66.

 

[Louie's gone fishing]

Gene Berg recommends Pennzoil GT Performance Racing 25w-50. It's because of the crummy valve train components. You can call them, ask for Tim. I don't think their recommendation has changed.

 

[Gary Allan]

quote:

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Originally posted by Eddie:
What does the Factory recomend? and what is the factory load as new? I thought it was Mobil 1 5w or 0w40?

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quote:

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I have a 66 Porsche 912

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I'd say that it was probably a good bit different then he puts in there now.

j/k

 

[Gary in Sandy Eggo]

As you drop the viscosity of the oil (synthetics tend to the lower end of the viscosity scale for any given "weight"), oil temperature will go down because thinner oils generate less internal shearing heat. However, thinner oils do not keep moving parts apart (plain bearings, cam lobes, cylinder wall to piston) as well as do thicker oils.

20W-50 will do a good job of keeping your moving parts apart. Mono-grade oils are even better when it comes to protecting an engine's moving parts, and they don't lose viscosity through VI improver shear since there's no VI improver to shear.

Regards, Gary in Sandy Eggo

 

[ediamiam]

I have used both 15w-40 and 30wt in my '67 912. Currently I have 30wt chevron in it. Engine rebuilt 3 years back, with full-flow filtering. That external filtering seems to keep the oil cooler, like having more cooling fins.

 

[Nickdfresh]

quote:

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Originally posted by ewetho:
For what it is worth Gene Berg of air cooled VW fame recommends Dino for use in air cooled motors for better heat ransfer. Now his data is several years old at this time but they did extensive research monitoring temps in all parts of the motor and post teardown analysis and found it is best. As for brand pick your favorite.

But then there are lots of Porches that ran Mobil1 very successfully so who know. Just and interesting side point I guess.

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I had this quandary years ago when I wanted to put Mobil 1 in my father's 79' convertible Beetle, and was told not too for the "heat dispersion" reason listed above. I ended up just using Pennzoil mineral.

However, I think it should be noted that the sump on a Beetle is about 3.75 qts. whereas an older air-cooled Porsche is about 14 qts. (my boss had an 80's vintage Porsche we put Mo1 15W-50 in). I would imagine that w/ 14 qts., heat dispersion may be less of a concern since Porches are essentially oil-cooled?

 

[ediamiam]

The 912 engine takes 4 qts. A 911 has the higher oil capacity.

 

[LarryL]

The Gene Berg recommendation comes from Jim Feuling, a guy that knows a lot about engines. In the late 90's he worked on the problem of lubrication for valve train components in air cooled engines. Later he developed the W3 motorcycle engine, just before his death in late 2002. So, even six or seven years ago the problem of lousy quality lifters was a pia.

 

[Pat in Speedway]

Since no one else has, I'll represent the Corvair community here. I've heard many of the same arguments regarding syns providing cooler temps. Since the engine in my '65 is somewhat worn and she's a leaker, I run 20W-50 conventional. I just stick with a name brand that's on sale. It's mainly driven 8 months out of the year, with temps ranging in the 50's-90's. However, if it was a little "tighter", I'd likely run a HD 15W-40.

 

[Lazy JW]

quote:

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Originally posted by Nickdfresh:


However, I think it should be noted that the sump on a Beetle is about 3.75 qts. whereas an older air-cooled Porsche is about 14 qts...

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Every Beetle I have changed oil on used closer to 2.5 qts. It isn't good to let them run a quart low.
Joe

 

[carock]

Okay, I am going to chime in here and claim to be an expert. Harry Pellow and I carried out many dyno runs and other experiments with Porsche 356/912 motors. I am also familiar with Gene Berg having run one of his engines 50,000 miles in my 67 Beetle. The ester based oils like Redline tranfer heat about 25% better than dino oils, not 25% worse than dino oils. Whoever found synthetics do not transfer heat as well as dinos was not using ester based synthetics. Redline's ability to transfer heat and resist high temperatures is what makes it so superior to dino oils in Porsche applications. Between Harry Pellow, Steve Ponder, Ron Lambert and myself, we have probably built and tested over 10,000 VW and Porsche motors for every conceivable use. Redline rocks in these engines, it flat blows dino oils away, no contest. The only problem is that it leaks. To prevent this Ron Lambert proved that introducing Redline oil into an older VW one quart at a time prevented leaks.Redline oil will give your Porsche a 50% increase in life.With the price of Porsche parts, you cannot afford to run anything else. Mobil has changed their formulas through the years. I think if you used the Mobil 1 V-twin oil in your 912 it might also work well but I only have experience with Redline.I am sorry to come out like a Redline advertisement, but for your air cooled Porsche it works much better than dino oil. You should also get a Frantz bypass oil filter to replace the standard bypass oil filter. The difference between regular oil and Frantz super clean oil could be dramatic and save you a lot of money.I wish I knew about these when I was working on Porsches. The Frantz filter hooks up the same as your regular filter but will use different brackets and hoses.See the bypass filter section. Remember, the 356 uses a pleated paper element, not a superior Frantz tissue paper element. Good luck with your 912, its a great car that outhandles 911's. Keep the faith!