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What factors do you use to determine oil viscosity? #1075523 09/15/11 02:14 PM 09/15/11 02:14 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	What factors do you use to determine the appropriate oil viscosity to use in your race (either track-only or street/strip, etc.) engine? - Bearing clearances? - Engine displacement? - RPM range? - HP expectation? - Valve train type (e.g. flat tappet vs. roller)? - Oil system design / volume? - Water and/or engine oil temperature? - Short-duration vs. endurance-type usage? - What the factory manual says? - What your engine builder told you to use? - What the guy who beat you last time uses? - What your sponsor gave you a case of?

Re: What factors do you use to determine oil viscosity? [Re: BradH] #1075524 09/15/11 02:50 PM 09/15/11 02:50 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	The last 2! Fastest 300

Re: What factors do you use to determine oil viscosity? [Re: BradH] #1075525 09/15/11 02:59 PM 09/15/11 02:59 PM
Joined: Jan 2003 Posts: 16,928 NC 440Jim I Live Here
440Jim I Live Here Joined: Jan 2003 Posts: 16,928 NC	I am not the authority on this, but my 2-cents: - Engine oil temperature - Bearing clearances - Oil system design / volume - Valve train type (e.g. flat tappet vs. roller) - HP expectation (ie bearing load) 1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1

Re: What factors do you use to determine oil viscosity? [Re: BradH] #1075526 09/15/11 04:57 PM 09/15/11 04:57 PM
Joined: Jan 2003 Posts: 31,046 Oregon A AndyF I Win
AndyF I Win A Joined: Jan 2003 Posts: 31,046 Oregon	An engr at an oil firm told me that engines want 30 wt oil which is 210 degrees. If it is colder than that then use a lighter oil. Heavier oil is used in special circumstances.

Re: What factors do you use to determine oil viscosity? [Re: 440Jim] #1075527 09/15/11 05:41 PM 09/15/11 05:41 PM
Joined: Jul 2008 Posts: 30,444 Florida STAYcation dOoC The village idiot's idiot
dOoC The village idiot's idiot Joined: Jul 2008 Posts: 30,444 Florida STAYcation	Quote: I am not the authority on this, but my 2-cents: - Engine oil temperature - Bearing clearances - Oil system design / volume - Valve train type (e.g. flat tappet vs. roller) - HP expectation (ie bearing load) ....AND rod side clearance

Re: What factors do you use to determine oil viscosity? [Re: dOoC] #1075528 09/15/11 09:17 PM 09/15/11 09:17 PM
Joined: Jan 2007 Posts: 7,664 IN A ahy master
ahy master A Joined: Jan 2007 Posts: 7,664 IN	To get in the ballpark, bearing clearance and type as well as oil pump (std, high volume). Also planned use. To fine tune, I use hot oil pressure. I prefer to see at least 20 psi at idle and a steady regulated pressure over 2000 RPM. On my stuff, I broke in with 10W30. Hot oil pressure was lower than I liked so I switched to 15W-40 and all is well. With performance bearing clearances and full groove main bearings mine likes a little heavier oil. Also, I street drive mine and it can see extended hot weather idling in traffic from time to time... I didn't want to have to worry about the cam/lifters and top end getting enough oil in that situation. If it were race only I probably would have stayed with 10W30 for the slight performance gain.

Re: What factors do you use to determine oil viscosity? [Re: ahy] #1075529 09/15/11 10:37 PM 09/15/11 10:37 PM
Joined: Jan 2003 Posts: 8,166 Plymouth, MI Blusmbl master
Blusmbl master Joined: Jan 2003 Posts: 8,166 Plymouth, MI	Engines that have rod/crank bearings undersized for the expected load (boost on an original n/a motor is a good example of this) will require a heavier weight oil. I'd consider expected oil temp & bearing clearance the other critical factors. '18 Ford Raptor, random motorcycles, 1968 Plymouth Fury III - 11.37 @ 118

Re: What factors do you use to determine oil viscosity? [Re: BradH] #1075530 09/16/11 02:28 AM 09/16/11 02:28 AM
Joined: Aug 2003 Posts: 43,218 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,218 Bend,OR USA	MY personel N/A drag race pump gas 5W20WT Valvoline non synthetic, same on the street High output(above 800 HP) drag race motor 10W30WT or 15w40 or 25W50WT Pennzsoil racing oil ,depending on the customers desires Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

Re: What factors do you use to determine oil viscosity? [Re: Cab_Burge] #1075531 09/16/11 03:32 AM 09/16/11 03:32 AM
Joined: Nov 2003 Posts: 6,293 Rock Springs Bob_Coomer master
Bob_Coomer master Joined: Nov 2003 Posts: 6,293 Rock Springs	My I dont consider Oil Viscosity when I set bearing clearance, so bearing clearance or any other bottom end spec shouldnt be a factor for selecting Oil. If you have 100 PSI at idle with thick oil, its a screw up anyways, and should be addressed, about 30% more oil pressure than needed. I run thicker oil for added protecting from "break down" I dont run the zero weight oil, and very light oil. Sorry but a 1% increase in performance isnt worth it. I try to run 15W-50. This oil has been around a long time, and is the best I have tried. I will run a Semi Synthetic on occasion. Great stuff here. Run a Accumulator, it will provide more protection than anything else. http://www.schaefferoil.com/ . . [color:"red"]65 Hemi Belvedere coming soon [/color] [color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]

Re: What factors do you use to determine oil viscosity? [Re: 440Jim] #1075532 09/16/11 12:26 PM 09/16/11 12:26 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: I am not the authority on this, but my 2-cents: - Engine oil temperature - Bearing clearances - Oil system design / volume - Valve train type (e.g. flat tappet vs. roller) - HP expectation (ie bearing load) And I'll mention that I'd never really thought about how some of those factors really play into this until seeing how the Joe Gibbs racing oils are partly defined in their application specs by things like bearing clearance and oil temps. The other thing which rarely seems to come up is what the High-Temp/High-Shear (HTHS) requirement is. There's a pretty strong correlation between higher HTHS values (e.g. > 5) and wear reduction on highly stressed/loaded components, yet it's not a commonly advertised rating. Part of that may be that the best HTHS values I've seen all come from 50-type wt oils (15w50, 20w50, straight 50 wt) and dropping down to 30 or 40 grade oils always shows a significant reduction in the HTHS ratings. For example, I pulled these from the Brad Penn product spec sheet: HTHS @ 150*C, cP 0w30 - 3.38 10w40 - 4.23 20w50 - 6.20 Last edited by BradH; 09/16/11 12:36 PM.

Re: What factors do you use to determine oil viscosity? [Re: BradH] #1075533 09/16/11 03:27 PM 09/16/11 03:27 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: ... Joe Gibbs racing oils are partly defined in their application specs by things like bearing clearance and oil temps. Stuff from Joe Gibbs Driven web site's Products pages: XP3 (10W-30) Synthetic - <List of various small-block competition series & engines...> - Engines with clearances under .0027 XP6 (15W-50) Synthetic - <Wider variety of engines...> - Engines designed for SAE 50 weight oils - Engines with oil temps 240-320* F XP7 (10W-40) Semi-synthetic - <Crate / spec engines w/ hyd. and/or flat-tappet cams...> - Engines with clearances under .0030 XP5 (20W-50) Semi-synthetic - Engines designed for SAE 50 weight oils - Engines with oil temps 220-260* F XP8 (5W-30) Petroleum - <"Small block / flat-tappet / N2O engines"> - Engines designed for SAE 50 weight oils - Engines with clearances under .0027 XP4 (15W-50) Petroleum - <"Big block / flat-tappet / N2O engines"> - Engines designed for SAE 50 weight oils - Engines with oil temps 200-240* F I'd be interested in knowing more of what defines "Engines designed for SAE 50 weight oils", but will assume for now it can be read as LOOSE. And going by their guidelines, I should definitely be running at least a ##w40 (or even a ##w50) in the MoPig, considering bearing clearances, expected oil temps, etc. Last edited by BradH; 09/16/11 03:33 PM.

Re: What factors do you use to determine oil viscosity? [Re: BradH] #1075534 09/16/11 03:51 PM 09/16/11 03:51 PM
Joined: Jan 2003 Posts: 1,855 Staten Island N.Y. Dap top fuel
Dap top fuel Joined: Jan 2003 Posts: 1,855 Staten Island N.Y.	Dwayne puts my stuff together. So it gets whatever he says to use.. PRH446 10.084 @ 135.21 mph N/A through chambered mufflers,3300lbs. Stock stroke wedge

Re: What factors do you use to determine oil viscosity? [Re: Dap] #1075535 09/16/11 04:25 PM 09/16/11 04:25 PM
Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually B BradH OP Taking time off to work on my car
BradH OP Taking time off to work on my car B Joined: Jan 2003 Posts: 15,439 Val-haul-ass... eventually	Quote: Dwayne puts my stuff together. So it gets whatever he says to use.. He tells me to run 20w50... but I keep having this occasional delusion that I'm smarter than him.

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