Use 5w50 instead of 20w50

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628
Location
LA (Lower Alabama)
Anybody got any comments on whether I should use a 5w50 (Castrol Syntec) instead of the 20w50 the engine manufacturer recommends. I don't suppose I should say what I'm putting it in because everybody seems to clam up and won't talk much about motorcycles, but it's for my '00 Harley Twin Cam 88. I'm going to do a dose of Auto RX so I needed a non-synthetic (Frank said Group III was OK) to run for only 750 miles and had a freebie from Sears ($20 gift card because they didn't change my tire in an hour). The Castrol 5w50 was the only 50 weight they had that was diesel rated (what Harley recommends if their oil isn't used). Anybody got any viscosity numbers on the 5w50? Castrol doesn't put MSDS's on the web and there are no VOA's or UOA's on this stuff, but in the Why-buy-any-other-synthetic-than-Mobil-1 thread someone suggested that the 5w50 might hold up better than M1 15w50 (which I am considering using later on). But since I'm only going to run it 750 miles, should I care just about the lower limits of protection rather than about the upper limits? BYW, the ambient temperatures here in Alabama are still in the 70's at night but it can get well into the 90's during the day.
 
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quote:
Originally posted by doyall: Anybody got any comments on whether I should use a 5w50 (Castrol Syntec) instead of the 20w50 the engine manufacturer recommends. I don't suppose I should say what I'm putting it in because everybody seems to clam up and won't talk much about motorcycles, but it's for my '00 Harley Twin Cam 88. I'm going to do a dose of Auto RX so I needed a non-synthetic (Frank said Group III was OK) to run for only 750 miles and had a freebie from Sears ($20 gift card because they didn't change my tire in an hour). The Castrol 5w50 was the only 50 weight they had that was diesel rated (what Harley recommends if their oil isn't used). Anybody got any viscosity numbers on the 5w50? Castrol doesn't put MSDS's on the web and there are no VOA's or UOA's on this stuff, but in the Why-buy-any-other-synthetic-than-Mobil-1 thread someone suggested that the 5w50 might hold up better than M1 15w50 (which I am considering using later on). But since I'm only going to run it 750 miles, should I care just about the lower limits of protection rather than about the upper limits? BYW, the ambient temperatures here in Alabama are still in the 70's at night but it can get well into the 90's during the day.
All else being equal, I would think that a narrow range oil like 15w50 would be more shear stable than a wider range like 5w50. Theoretically the 5w50 might give you less wear on cold starts, but would be more likely to shear down. Why are you only running the oil for 750 miles? If your interval is that short it's not going to have a chance to deteriorate so you can run just about any oil of the recommended weight.
 
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5,358
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Gone
doyall, I vote for the 20W50...I don't have anything against the 5W50, I just the think in your Harley that's the way to go.
 

CJH

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489
Location
Pennsylvania
You may get a lot better response if you posted your question in the MOTORCYCLE thread on this board.
quote:
Originally posted by pscholte: doyall, I vote for the 20W50...I don't have anything against the 5W50, I just the think in your Harley that's the way to go.
 
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509
Location
Las Vegas, NV
doyall, I think Castrol Syntec will be fine for a short interval in your Harley. Syntec 5W-50 data: ACEA A3/B3 and API SL/CF
code:
Viscosity, cSt @40 C  110
Viscosity, cSt @ 100C 17.5 
Viscosity Index       175
Low temp. CCS         <6600 (-30 C)
HT/HS viscosity       4.5
Flash Point           437 F (225 C)
Fire Point            >450 F (232 C)
Pour point            -39C
Zinc % wt             0.11
Phosphorus % wt       0.09

I would be very surprised if you had any trouble from running 5W-50 for such a short interval. I would however suggest keeping the AutoRX in a little longer. 850-1,000 miles might be a good idea to be sure you get all of the crud out of your motor. You would not want to have to order more AutoRX just to remove a little leftover crud. While I think Syntec 5W-50 is an OK choice for this short interval I think a fully synthetic 15W-50 or 20W-50 is a better choice for a normal oil change routine in a Harley. I would have purchased the Syntec 5W-50 if I had that coupon so I agree that you made a good decision. [ August 22, 2003, 07:30 PM: Message edited by: Sin City ]
 
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4,272
Location
Central Arkansastan
If your going to use either one 'exclusively', then I would go with the Mobile 15w-50. Especially in a Harley. I think after you read the various posts on either of these oils, M1 wins out.
 
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9,448
Location
USA
I would not use Syntec 5W50 in anything. First it is not a true synthetic it is group III conventional oil. Second the group III oils are only good up to 30Wt. so alot of VII's have to be added to get that spread of 5W50. VII's do nothing to lubricate or protect. If you are going to spend that time of money for a 50Wt. get the M1 15W50.
 
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2,363
Location
Texas
Everyone, I copied this thread to the motorcycle lubrication heading. that way the original poster can get info both places. Dan [ August 23, 2003, 01:51 PM: Message edited by: Dan4510 ]
 
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9
Location
East Coast
I have done a few searches for this info myself, is there a site (other than this one) that could explain why Sentec isn't a synthetic oil to someone with a public school education? [I dont know] [ August 23, 2003, 11:10 PM: Message edited by: ssnsltd ]
 
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