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Join Date: Mar 2001
Posts: 979
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1991 C2 tried synthetic oil for first time Leaking like crazy
I will be doing an oil change soon. Going back to conventional. Should I go back to Castrol 20/50 or something like 10/30?
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08-24-2025, 04:52 PM
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it all depend where do you live-climate-wise. 20W50 is the best bet mineral.But i would at this time look where was the oil leak ..too.
Ivan
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1985 911 with original 501 587 miles...807 226 km "The difference between genius and stupidity is that, genius has its limits". Albert Einstein. |
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08-24-2025, 11:16 PM
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Same experience on my SC. Switched back to all mineral engine oil (20W50 Liqui Moly touring high tech) and it's bone dry now. Todays all mineral oils are not comparable to mineral oils those days. Yes, the choice of (engine and gearbox) oil is a matter of climate and operating conditions. Look what Porsche says in the manual:
 Further reading: https://forums.pelicanparts.com/porsche-964-993-technical-forum/957141-0w-40-15w-50-mobil-1-a-2.html Synthetic oils require an elastomer stabilizer as additive not to shrink all elastomer/rubber based engine seals. All mineral oils does not need this as they refresh the rubber seals by nature. If the dose is too low (due to budget requirements) the seals shrink and engine tends to leaks... Truth is also: A refreshed and fresh sealed engine wont leak, no matter which oil is filled in.
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1981 911 SC Coupé, platinum met. (former tin (zinc) metallic), Bilstein shocks, 915/61,930/16,WebCam20/21, Dansk 92.502SD,123ignition distributor with Permatune box as amplifier,Seine Systems Gate Shift Kit,Momo Prototipo. Want to get in touch with former owners of the car. Last registration in US was in 2013 in Lincolnshire/lL. Last edited by Schulisco; 08-25-2025 at 06:02 AM.. |
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08-25-2025, 05:45 AM
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Still here
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Which synthetic ?
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08-25-2025, 07:15 AM
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Join Date: May 2009
Location: Around Boston
Posts: 2,004
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Quote:
Where do you live?
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RSA Pinky Helga Turtle Carrera Luigi CDtdi |
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08-25-2025, 12:20 PM
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My last acquisition had active leaks when I bought it.
Drained the oil and noticed it was synthetic. Went back in with Valvoline VR1 (zinc) 20W/50. Bone dry now. |
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08-25-2025, 02:11 PM
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08-25-2025, 04:54 PM
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Don
Join Date: Sep 2011
Posts: 100
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I'm using Ecorsa 20/50 in my 3L and no leaks.
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08-25-2025, 07:18 PM
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Location: Around Boston
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Go to a thicker mineral oil
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08-26-2025, 03:49 AM
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Posts: 979
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How about this?
Valvoline VR1 Racing SAE 20W-50 |
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08-26-2025, 05:21 PM
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Location: Allentown, PA
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08-27-2025, 04:51 PM
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Lash
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1980 911 SC
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Lash 1963 356 T-6 Normal Coupe 1972 911 T Coupe ..... Sold 1972 911 S Targa ...... Sold 1980 911 SC Coupe Weissach |
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08-27-2025, 07:38 PM
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Quote:
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1986 Porsche 911 Carrera 3.2 |
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08-27-2025, 07:47 PM
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Posts: 147
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Quote:
tried some others in the past (Castrol, Mobil,...) and had super results with Swepco 15W40, but because it was harder to get I switched to Valvoline VR1 racing 20W50 happy customer, not gonna switch anymore |
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08-27-2025, 11:28 PM
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Still here
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Quote:
1st rule is to get the viscosity right. |
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08-28-2025, 07:48 PM
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Join Date: Feb 2025
Posts: 19
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I use the vr1 also.
Even my local auto parts store stocks it. It's easy to locate online also for reasonable prices. I just replaced valve covers, triangle of death, oil cooler seals, new oil hoses, etc. All the gaskets and seals I could on my engine when the engine was out, when i pulled it for the clutch job. I have about 250 miles on it but no leaks. |
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08-28-2025, 08:17 PM
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I could be wrong but the most current Porsche recommendation is Porsche Classic 10w-60w synthetic. 15w-50w for M1.
I use VR1 |
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08-29-2025, 02:35 AM
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Gents,
are you aware, that the VR1 20W50 is a high zinc oil with 1400ppm....? And that it's not recommended for catalytic converters? https://www.valvolineglobal.com/en/vr1-racing-motor-oil-sae-40/ Of course with high zinc the engine benefits for wear. But as I suppose most of you still carrying a catalyst in your Porsches in the US this could go bad. If the cat is removed then its no problem of course... E.g. the Liqui Moly Touring High Tech 20W50 I personally use contains about 1100ppm of zinc which is high enough for wear protection but not too high for catalysts.
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1981 911 SC Coupé, platinum met. (former tin (zinc) metallic), Bilstein shocks, 915/61,930/16,WebCam20/21, Dansk 92.502SD,123ignition distributor with Permatune box as amplifier,Seine Systems Gate Shift Kit,Momo Prototipo. Want to get in touch with former owners of the car. Last registration in US was in 2013 in Lincolnshire/lL. Last edited by Schulisco; 08-30-2025 at 04:39 AM.. |
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08-29-2025, 03:37 PM
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Still here
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Quote:
Must be cold where the OP is. 
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08-29-2025, 05:37 PM
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Location: Allentown, PA
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Quote:
  
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08-29-2025, 08:19 PM
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Porsche 911 SC
Black Label
