20W50 oil
Senior User
Joined: Sep 2000
Posts: 385
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From: Flat Rock, Michigan
20W50 oil
My 81 F-150 with 187,500 miles has been getting its oil changed every 3,000 miles for the last 19 years faithfully. She doesn't burn or consume any oil in between changes. I drive 50 miles round-trip everyday to work on I-75 at 65-75 MPH. No problem for her to do the highway cruise except that after i get into the city i notice the oil pressure being pretty low. She drops into the "N" (N*ORMAL)range on the guage. Out on the highway or on a cold start the pressure is on the "L" (almost pegging the guage). I have found that using 20W50 oil vs 10W30 or 10W40 helps with the low pressure, but not a whole lot. With the higher miles on the engine i know that bearing clearances are increasing probally causing the lower oil pressure readings after she's been run for 30 minutes at 70 MPH. I have only slight valve tapping which comes and goes at an idle and seems to be more noticeable during the summer months.
Are there any other oil recommendations or additives that would help with a higher mileage engine? I have used Duralube at 99,000 miles and again at 150,000 miles. I use only FRAM or MOTORCRAFT oil filters. Any comments will be appreciated.
Are there any other oil recommendations or additives that would help with a higher mileage engine? I have used Duralube at 99,000 miles and again at 150,000 miles. I use only FRAM or MOTORCRAFT oil filters. Any comments will be appreciated.
Post Fiend
Joined: Jan 2000
Posts: 5,860
Likes: 4
From: Metro Detroit (Redford)
20W50 oil
Since it dosen't use any oil I don't think the rings or valve guide seals are bad. I would run 10w30 with a quart of Rislone every oil change. Yeah, Rislone is as thin as ATF, but that dosen't seem to matter. My recently sold '84 300 I6 has 176,000 miles and had rislone every change and it runs great, but the oil pressure on it sometimes read near the top of the safe range. Also the 84 would have a valve/lifter ticking once in a while. I don't know why the pressure would sometimes read high, but maybe the sending unit could be bad. They are cheap. May want to replace and see if the pressure reads better. Also, a mechanical oil gauge used for testing probably is more accurate to check true pressure. I was getting a very low pressure reading on my '95 300 I6 which turned out to a loose wire connection at the sending unit.
Postmaster
Joined: Jul 1999
Posts: 3,172
Likes: 4
20W50 oil
Along with checking the oil pressure sending unit , checking the Instrument voltage regulator may yeild a cause of the erratic gauge operation . I found my Ivr contacts had accumulated a fair amount of dust over the yrs & it wasnt really making a good contact with the instrument cluster circuit board . The Ivr has 3 copper pins that are bent so they provide some tension on the circuit board . I lightly bent the pins so that they made better contact & cleaned the dust off . This got rid of the erratic operation of my oil pressure gauge .
Freshman User
Joined: Jun 2000
Posts: 27
Likes: 0
20W50 oil
You might try a straight 30W oil. When Ford first started selling and using Multi Viscosity oil they sent an advisory to dealers that stated; DO NOT USE MULTI WEIGHT OIL IN HEAVY TRUCKS!! Do not ask me how old I am! --S Falkner
Fleet Mechanic
Joined: Aug 2000
Posts: 1,504
Likes: 1
From: Texas
20W50 oil
Paul,
In your opinion what would make an oil pressure guage on an 88 F-150 almost peg out at startup, stay there until the engine warms up and then move down into the "high" normal range? This has been bugging me for almost a year now.
1988 F-150 Custom to XLT Lariat conversion, 5.0 EFI (formerly 300 I6), 5-speed M5OD, 3.08 rear gears (will be upgraded to 3.55's), Summit headers, Flowmaster muffler W/ dual 3.5" tips 24" long.
Pioneer CD, AC, Tilt, Cruise, Mobile Radio, Lightbar (Force 4 LP6000), Federal Signal PA300 Siren W/100W Siren Speaker. Caution Customizing in progress, Watch for flying tools & Parts!
In your opinion what would make an oil pressure guage on an 88 F-150 almost peg out at startup, stay there until the engine warms up and then move down into the "high" normal range? This has been bugging me for almost a year now.
1988 F-150 Custom to XLT Lariat conversion, 5.0 EFI (formerly 300 I6), 5-speed M5OD, 3.08 rear gears (will be upgraded to 3.55's), Summit headers, Flowmaster muffler W/ dual 3.5" tips 24" long.
Pioneer CD, AC, Tilt, Cruise, Mobile Radio, Lightbar (Force 4 LP6000), Federal Signal PA300 Siren W/100W Siren Speaker. Caution Customizing in progress, Watch for flying tools & Parts!
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