20w50 Synth - 80 Porsche 924

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9
Location
Regina, Sask, Canada
I recently aquired a 1980 Porsche 924. It has nearly 60,000km (37,260Mi). It had been using 20w50 before, and I want to use a synthetic oil. Wondering which brand is best I browsed around on different oil company's sites, and noticed that most of the big brands don't sell a 20w50 synthetic oil. Valvoline was the only brand that had it. But after reading a few threads, Valvoline might not be a very good oil to use and that its not actually a real synthetic. Should I use the valvoline 20w50 (recommend weight) or should I switch the weight and use a better brand like mobil 1. Cost is a factor and I can't afford the most expensive specialty stuff out there, however it is a small one and I want to extend the life of this car for a VERY long time.
 

Patman

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21,990
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Oakville, Ontario
Mobil 1 15w50 would be a good choice, if indeed that engine does need a thick 50wt oil. What does the manual recommend? Although I just noticed you live very close to a Schaeffer distributor (he's in Moose Jaw), so you might want to look into their line of oils too. [ May 26, 2003, 03:30 PM: Message edited by: Patman ]
 

Solidox

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9
Location
Regina, Sask, Canada
Well I don't have the OEM manual but I have the Haynes Manual.
quote:
Havey duty oils of SD or Se specification Summer: SAE 30 weight Winter: SAE 20 weight For continuos operation between -15 and 0 degrees celsius SAE 20 W 20 weight For continuous operation below -15 degrees celsius SAE 10 weight
 

Patman

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Oakville, Ontario
Then I have to ask the question, why did you want to continue using the thicker 20w50 oil? You're just robbing the engine of power and MPG, while most likely causing more engine wear too.
 

Solidox

Thread starter
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9
Location
Regina, Sask, Canada
No there's no oil temp. gauge. What exactly do the numbers in the viscosity rating mean? Is it better to run too low a weight or too high a weight? I have some more information that might help us find what oil is best suited for my car.
quote:
Engine Lubrication Lubrication: Pressure type lubricating system with a rotary (sickle-type) pump System oil pressure (at 2,000RPM): 5 to 7 bar (71 to 100 psi) at 80° to 100°C (176° to 212°F) Maximum oil temperature: 150°C (302°F)
[ May 26, 2003, 04:28 PM: Message edited by: Solidox ]
 

Patman

Staff member
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21,990
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Oakville, Ontario
quote:
Originally posted by Solidox: No there's no oil temp. gauge. What exactly do the numbers in the viscosity rating mean? Is it better to run too low a weight or too high a weight?
That's a difficult question really, because in either case it'll result in higher engine wear if you're not running the optimum viscosity for your engine. Keep in mind that it's not going to be catastrophic though (at least not over the short term). Ideally what you want to do is get oil analysis done and see how the wear numbers look and adjust up or down from there. As far as the numbers in the viscosity of an oil, the first number refers to how well the oil pumps at low temperatures (contrary to popular belief, the first number is not an actual viscosity). The lower numbers pump better in extreme cold temps. The second number is an actual viscosity, measured at 100c. In order to be an Xw20 oil, the viscosity must be between 5.6 to 9.3cst at 100c. To be an Xw30, it must be between 9.3 to 12.5cst at 100c, and to be an Xw40, it must be between 12.5 to 16.3. A 50wt is from 16.3 up to about 22 or 23 cst I believe. Another thing to keep in mind is that a quality synthetic can protect as well as a thicker conventional oil would, but without the horsepower loss or MPG drop. So if someone's engine calls for 10w40 in the summer, they could safely run a good 5w30 or 10w30 synthetic.
 
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From my recent trip to Porsche dealership: "We use M-1 0-40 in the new Porsches....15-50 in the older models as per Porsche Canada" If it's an 80 model...wow only [email protected]#@$!..it's most likely recommending the 20-50 as you suggested and you could use either that or Mobil 1 15-50 without problems. The verdict is still out on thinner vs. thick....the best advice is to use what's recommended. Why not check out roadfly.com porsche message board and see what other owner's recommend.
 

Patman

Staff member
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21,990
Location
Oakville, Ontario
quote:
Originally posted by Dr. T: From my recent trip to Porsche dealership: "We use M-1 0-40 in the new Porsches....15-50 in the older models as per Porsche Canada" If it's an 80 model...wow only [email protected]#@$!..it's most likely recommending the 20-50 as you suggested and you could use either that or Mobil 1 15-50 without problems. The verdict is still out on thinner vs. thick....the best advice is to use what's recommended. Why not check out roadfly.com porsche message board and see what other owner's recommend.
That's a good idea, as possibly some of them might have oil analysis reports as well, so you can get a general idea of which viscosity and which oil works well in this engine.
 
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