Motor Oil
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Senior User
Joined: Aug 2008
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From: Tuscumbia , Al
Motor Oil
78 F150 460 engine, I live in Alabama so its not too cold here LOL I was thinking of using 20w 50 or straight 50w what do you think ?? I am turning 3000 rpm @ 60-65 mph . it was ok before mods. cam , gears , ect. running 10w 40 but now the more rpm's the lower the oil pressure !! 
Hotshot
Joined: Dec 2003
Posts: 18,423
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From: iowa
if your dropping oil pressure with higher rpms you have something else wrong. Are you using a mechanical gauge? If not put one on and find out what yoru oil pressure really is.
I was running 10w-40 in my 900+hp race engine at over 7500rpms (over 8k on occasion) with no issues even in Aug at 100 deg days with oil temps over 225.
I was running 10w-40 in my 900+hp race engine at over 7500rpms (over 8k on occasion) with no issues even in Aug at 100 deg days with oil temps over 225.
Senior User
Joined: Nov 2008
Posts: 276
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From: Nashville NC
Things I've learned about oil presure.
To high a crankcase level & the crank will hit the oil & cause air to mix in make the presure drop.
If you have a rear sump pan & the long pickup tube from the pump, that tube can crack & pull air through the crack causing the presure to drop, happened to my engine reason I know that.
Need to think what the end of the dizzy shaft got to do trying to turn that oil pump shaft. I never thought about it untill I tryed to prime the engine with oil. Had 20/50 at the time in the pan & almost burt up a 3/8s drill before oil got to the rocker arms.
I have a new respect when starting up a cold engine & those wheel dont move till the temps are up & the oil presure drops just a tad.
Oh, & that monsterbaby guy, hes the man, got something up in that knoggin bout them 460 Fords.
Neil
To high a crankcase level & the crank will hit the oil & cause air to mix in make the presure drop.
If you have a rear sump pan & the long pickup tube from the pump, that tube can crack & pull air through the crack causing the presure to drop, happened to my engine reason I know that.
Need to think what the end of the dizzy shaft got to do trying to turn that oil pump shaft. I never thought about it untill I tryed to prime the engine with oil. Had 20/50 at the time in the pan & almost burt up a 3/8s drill before oil got to the rocker arms.
I have a new respect when starting up a cold engine & those wheel dont move till the temps are up & the oil presure drops just a tad.
Oh, & that monsterbaby guy, hes the man, got something up in that knoggin bout them 460 Fords.
Neil
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Joined: Mar 2007
Posts: 1,191
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78 F150 460 engine, I live in Alabama so its not too cold here LOL I was thinking of using 20w 50 or straight 50w what do you think ?? I am turning 3000 rpm @ 60-65 mph . it was ok before mods. cam , gears , ect. running 10w 40 but now the more rpm's the lower the oil pressure !!
I dont know how many miles are on the bottom end, Guages and sending units go bad, so you must rule that out... Try a mechanical gueage.
If that is not it, It may either be your crank bearings wearing out, or you nicked a cam bearing when changing the cam..
Oil preassure is built, and held by bearings tight tolerences. Kinda like a water hose. when you put your thumb over the end, it doesnt just pour out, it starts to spray. The more preassure from your thumb, the further it sprays. The bearing surface is your thumb, and the oil passages in the crank is the hose. Loose tolerances less preassure.
Thicker oil will temperarily raise preassure but will not be a cure all.
I dont know that I would reccomend 50w oil though.
Most race engines use straight 30w. especiaaly higher reving ones. I wouldnt go any higher then straight 30w, and would only use it above 65 degrees.
Hotshot
Joined: Dec 2003
Posts: 18,423
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From: iowa
Do you have a point your wanting to make?
yeah ok
That MIGHT have been true 40 yrs ago. No legit pro or semi pro racer runs straight 30w and hasn't' for a very long time, only wannabe street racers.
example most the Nascar teams are running 5w-20, drag racers are running 0w oils (0w-20 and 0w-30) straight 30w is so old school it's not even talked about anymore in any legit racing circles
yeah ok
That MIGHT have been true 40 yrs ago. No legit pro or semi pro racer runs straight 30w and hasn't' for a very long time, only wannabe street racers.
example most the Nascar teams are running 5w-20, drag racers are running 0w oils (0w-20 and 0w-30) straight 30w is so old school it's not even talked about anymore in any legit racing circles
