Oil used and fuel pressure

Discussion in 'Questions From New Drivers' started by Pete475, Jun 19, 2021.

  1. Pete475

    Pete475 Bobtail Member

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    Dec 13, 2020
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    Good Morning all. 2 questions that I have been researching on the interweb and can't get a definitive answer on. Maybe you can shed some light.
    Background C15 Acert bumped up to 550 Hp. 1820 on the TQ with 98k on out of frame rebuild.

    1. I run Rotella oil. I do my oil changes at 20k. Up to 10k on the oil change I use no oil. After that I use somewhere about a gallon every 1000 miles. Has anyone eles have this problem? What's the oil for a C15?

    2. When I'm running down the road at 71 mph my fuel pressure is between 85 and 90 PSI. What is the standard fuel pressure for this motor?
     
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  3. kemosabi49

    kemosabi49 Trucker Forum STAFF Staff Member

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    1. Start getting an oil analysis at oil change and at 10,000 miles and see what happening with your motor. I had the same problem many years ago and it went away when I switched to Delvac. My oil pressure would start dropping a little around the 10,00 mile mark.
    Can't tell you about 2.
     
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  4. Long FLD

    Long FLD Road Train Member

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    20k is going pretty extreme on a Cat. But…are you adding a gallon as soon as it’s a gallon low? Have you ever tried running it with the dipstick showing a gallon low and see what happens? Cats kinda had the reputation for burning a gallon off and just staying there until service. But if you’re really burning a gallon every 1000 miles once past 10k then your engine is telling you to stop doing that. You’re basically doing an oil change without changing the filters.
     
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  5. Frank Speak

    Frank Speak Road Train Member

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    For the non mechanic (that would be me), I have to ask, why are you looking at fuel pressure when you’re worried about oil usage? Wouldn’t you pay more attention to oil pressure?

    Related, I drive a Peterbilt 389 and with fresh oil, the oil pressure is around 60 psi at 70 or so mph. The older the oil, the less pressure until it gets close to service being due where it ends up at around 40 psi at 70 or so mph.

    I told the boss man (owner of the truck) about this and he says it’s fine. They’ve had the oil analyzed at different mileages and said it’s good to go.

    Go figure...
     
  6. Pete475

    Pete475 Bobtail Member

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    Oil pressure is over 60 all the time. Not worried about that. I have heard the fuel pressure is about 110. Just trying to find out for sure.
     
  7. Pete475

    Pete475 Bobtail Member

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    Dec 13, 2020
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    Oil pressure is over 60 all the time. Not worried about that. I have heard the fuel pressure is about 110. Just trying to find out for sure.
     
  8. Pete475

    Pete475 Bobtail Member

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    Are you using Delvac extream or the 1300
     
  9. lester

    lester Road Train Member

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    Your fuel pressure is fine. Maybe a touch on the low side but nothing to be concerned aboot.

    I always figure once the truck starts burning oil it's time to change it. So if you go 10,000 with no usage then start burning it after that I'd change at 10
     
  10. Pete475

    Pete475 Bobtail Member

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    Dec 13, 2020
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    Thanks. I use Rotella now. But was thinking about trying something different to see if it could just be the oil. I don't know if I'm off base on that or not. I had a car that did the same thing. Would go through penzoil between changes. When I switched to Valvoline it stopped.
     
  11. lester

    lester Road Train Member

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    I ran Rotella and switched to Delo. Seems to burn a little less and perhaps less blow by. Doesn't smell as much out the blow by anyway.

    Lot of guys say Rotella is junk nowadays. I dunno
     
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