Diesel information for the new owner

waterdude007waterdude007 Member Posts: 1
edited March 2014 in Ford
I just purchased a 1991 Ford F-250 7.3 liter diesel. This is my first diesel truck or car that I have ever owned, so some sound advice is needed.

Changing the oil every 3,000 miles with a quality oil made for diesel engines, favorite brands and grades/weights?

I heard the I should fill my truck with fuel where the big rigs fill up, because then those fuel stations have better turn over and less water in the fuel, True or False?

Advice on coolant changes, routine maintenance? Should I take it to the local Ford dealer and bend over? Or find a good independent mechanic and make a friend?

My rig: 1991 3/4 ton with over rider springs, with only a bumper pull (never had a frame mounted hitch, but it will soon), 5 speed manual, 7.3L diesel, XLT Lariat, AC (not pushing any cold air), body is straight and very clean, 133,000 miles, all for $5700.

I removed the oil filler cap while the motor was running and saw "no blow-by" smoke. I heard that that meant it was well maintained with frequent oil changes, True/false?

Thanks for any and all advice, Hugh


  • quadrunner500quadrunner500 Member Posts: 2,721
    CG-4, CH-4, or what's recommended by Ford for the oil. Shell Rotella, Chevron Delo, Valvoline Fleet or Premium Blue, Mobil Delvac, your choice.

    If the fuel station advertises "premium diesel," the API has established guidelines that the consumer must realize at least one of three actual, not perceived benefits, mileage/power, lubricity, emissions reduction. This is what I use, but you can never know what you're getting, so don't worry much. I try and buy all my fuel from the same place. I also won't buy from a dealer doing oil changes, since some have been known to mix motor oil with diesel. Just my $0.02

    Since your truck is 10 years old, I would run some biocide to dissolve sludge, slime, bacteria growth in the fuel tank, drive it, and change the fuel filter some time after. There's a petcock or lever to drain off water from the fuel/water separator on or near the fuel filter. Do this. Should be explained in the manual.

    I would definitely change the coolant, since that's often overlooked. Check for any special "bleed" procedures.

    True on the test for blow-by. Sounds like a good price.
  • bobsquatchbobsquatch Member Posts: 136
    There is a special coolant additive you must put in your cooling system to prevent cavitation corrosion in your block behind your cylinder sleeves. This is paramount as the slightest leak will ruin your engine buy leaking coolant into your oil. Any ford dealer or diesel shop can tell you what you need.
  • quadrunner500quadrunner500 Member Posts: 2,721
    ...have cylinder sleeves.
  • markbuckmarkbuck Member Posts: 1,021
    Agree, but his IDI 7.3L need the potassium hydroxide solution available at your ford dealership.

    Use 15W-40 oil, I like Delo 400, Rotella, or Valvoline Blue. Use Ford's FL-784 oil filter, if I remember right, got em at Walmart.

    Keep fresh air filters in the thing, and try to drive it someplace once a week for a long trip to get it hot.

    Oh ya, injector pumps go out every now and then, and check your glow plugs every fall. You can get Motorcraft glow plugs at AutoZone off the shelf.
  • joe3891joe3891 Member Posts: 759
    Have the coolant checked for the anti-cavitation chemical with a test kit,then they will add whats needed.I have seen the blocks with holes in them.
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