Help settle an oil debate

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Figure this is the place to do it... My half-brother has an 89 944 turbo. He has around ~70 thou on it. He currently runs M1 EP 15-50 in it. In the winter he runs M1 10-40 HM in it. I tell him he'd be better off running M1 0W-40 in it all year round or some GC. Let's hear some expert thoughts!!
 
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What does the owner's manual recommend? But yeah, Mobil seems to recommend 0w-40 and Amsoil recommends their 5w-40 in this application.
 
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4,998
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Milwaukee, WI
I would agree that the 944 would run fine on 0/5w-40 year round. But I don't understand what he would gain. He would still use the same amount of oil, so the cost would be the same assuming he doesn't keep large stocks of inventory that could be halved. And he wouldn't be as happy as he is now. This just isn't a right and wrong, and if he's happy, well, it's his car.
 
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Aridzona
Where does he live? (How cold does it get in the winter?) IMO, if he doesn't get much below freezing, he'll be fine as is. 0W-40 or 10W-30HM, will both have better pour points (and presumably better low temp startup flow) than his 10W40HM winter choice.
 
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11,184
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Bad Axe, MI
What he's doing is fine IMO,i run M1 10w30HM all winter long(-54pp)no problems. The 15w50 will help with the heat that turbo puts out.or the 0w40 would work too,it doesn't really matter what he chooses both great oil's and will work. the only thing i would change is to run the 10w30HM instead of the 40 in the winter.
 
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Retired | Wausau, WI
Hope FrankN4 sees this thread. He uses Mobil 1 15W-50 in everything he and his family has and uses it year round. If it ain't broke, don't fix it. I sent FrankN4 a PM so maybe he will jump in.
 
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mmmmoil

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 Originally Posted By: Geonerd
Where does he live? (How cold does it get in the winter?)
columbus ohio around 20's for high in jan
 
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Airlie Beach Australia
Hi, mmmmoil - I can't settle your debate for you but the 944's engine will certainly be best served by using a 0W-40 or 5W-40 semi/fully synthetic lubricant to A3/B3 spec - or one that is Approved and Listed by Porsche Two of my closest friends here have 944S2 cars - (one has owned his since new - the other owner is an ex EM Executive) and both have been on such lubricants for most of their lives. One car has 160kkms on it - oil consumption is zero in each case There is nothing "wrong" in using the 15W-50 lubricant but Porsche have methodically reduced its cold start lubricant specification to 0W/5W since the mid 1980s - they only specify one SAE50 lubricant - M1 5W-50! That said, German privateer racers of these cars use 15W-50 and 10W-60 synthetic lubricants in these engines - preheated to 80C before being "loaded" of course If it was my car I would be using M1 0W-40 or M1 TDT 5W-40 all year round
 
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 Originally Posted By: Johnny
Hope FrankN4 sees this thread. He uses Mobil 1 15W-50 in everything he and his family has and uses it year round. If it ain't broke, don't fix it. I sent FrankN4 a PM so maybe he will jump in.
First. let me say that I have absolutely no brand loyalty. If I find something tomorrow that meets all of my requirements better than Mobil 1 15W-50, I will change tomorrow. Mobil 1 15W-50 has a pour point of -39. That is the same as many 40 grade oils. 0W-20 through 10W-30 run pour points of -40 to around -45, basically, there are exceptions. This past winter, we had 8 to10 days where the night time temperature dropped below 10F, but none below 0F. My Toyota, Cavalier, and Silverado all started literally before you could release the key. 0F definitely not to cold. I have heard it said that a 0W-30 would pump/circulate faster than a 15W-50. Many years ago I was adjusting the valves on a motorcycle that had the nut and bolt adjusters. I pulled the plugs so it was easy to turn the engine and keep it where I wanted. I had my wife push the kick start to turn the engine. I noticed oil flowing in the heads just from the kick start pressure, and it flowed immediately. This was a 20W-60 conventional oil. I looked under the valve covers of some of my vehicles with a bore scope/light. I removed plug wires or distributor wire and cranked engine. Oil flowed immediately with just a tap on the starter. Because of this, I PERSONALLY, do not believe there is any appreciable oil flow advantages to a XW-20 or 30. Mobil 1 15W-50 has a 40C cSt of 131.2. Rather low for a 50 grade. It has a 100C cSt of 18.1. Again, low for a 50 grade. The HTHS is only 4.5. Mobil 1 15W-50 is by no means a thick oil. Just look at the PDS for other 5w/15W/20W-50 oils. I run mostly low RPM engines and Mobil 1 15W-50 is easily thick enough to be pumped by the low peripheral velocity of my journals. It also has the viscosity reserve for the 230F oil temps across the Smoked Mountains with camper pack and trailer. If Mobil 1 15W-50 were just a little more viscous or just a little less viscous, had a lower HTHS, had a different add pack, I would not even consider its use. I do not believe there is any measurable difference in gas mileage between a 5W-20 and a 15W-50. Just look at the API web site. Uneven tire pressure, running with open windows, air density, air temperature, the way you drive, where you drive, all will have more effect on fuel use than viscosity. Mobil 1 15W-50 is SM rated and it has a ZDDP pack of 1200. Not overly high but more than sufficient for my uses. The calcium content is not so high to compete with the ZDDP but not so low to not effectively keep the engine clean. I do not want to write a book here. I know of nothing better for my use in my geographic location. I would probably consider something different for winter use if I lived in Frostbite Falls. I might should add that since 1990, I have 2,000,000 miles on M1 15W-50 with never an engine problem, no consumption at all, no leaks, no seeps, and always better than EPA estimates. I ran it in everything from DOHC SMPFI 1.5L I4 engines to big GM V8 engines. If Amsoil, Mobil, Pennzoil, or Valvoline were to come out with a GPIII, GP III/IV blend, or a GP IV oil,(I PERSONALLY prefer the III/IV blend) 40C cSt of at least 80, 100C cSt of at least 13.5, SM level ZDDP with a moly reinforcement of about 300, absolutely shear stable over 3000-3500 miles, HTHS of at least 3.8, a heavy FM content, low(1 or less) SA, that might entice me to look seriously at a thin oil.
 
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11,247
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PA
It would be good for the turbo to be lubed asap. My mechanicshas a lot of 944T Club Racers as customers and he reports a lot of failures on M1 Red Cap. He uses Syntec 5w-50. In that car in winter, I'd run GC or M1 0w-40, but imo, Rotella Synth 5w-40 would be the best all-around choice as long as oil temps are in check. M1 10w-40 is good stuff though. I just don't like Red Cap.
 
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CA
 Originally Posted By: Audi Junkie
It would be good for the turbo to be lubed asap. My mechanicshas a lot of 944T Club Racers as customers and he reports a lot of failures on M1 Red Cap. He uses Syntec 5w-50. In that car in winter, I'd run GC or M1 0w-40, but imo, Rotella Synth 5w-40 would be the best all-around choice as long as oil temps are in check. M1 10w-40 is good stuff though. I just don't like Red Cap.
The turbo recieves lube extremely fast, it's not an issue.
 
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11,184
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Bad Axe, MI
 Originally Posted By: BuickGN
 Originally Posted By: Audi Junkie
It would be good for the turbo to be lubed asap. My mechanicshas a lot of 944T Club Racers as customers and he reports a lot of failures on M1 Red Cap. He uses Syntec 5w-50. In that car in winter, I'd run GC or M1 0w-40, but imo, Rotella Synth 5w-40 would be the best all-around choice as long as oil temps are in check. M1 10w-40 is good stuff though. I just don't like Red Cap.
The turbo recieves lube extremely fast, it's not an issue.
^^^ Exactly
 
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N.H, U.S.A.
Why WASTE ENERGY running a 50wt when it absolutely not required on a street car. Wasted fuel, Wasted power. Period. I bet you thick guys wear two pairs of underpants too ;\)
 
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