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  1. #1
    Jr. Engineer
    Join Date
    Mar 2010
    Cochrane, AB

    Default Worth switching Engine Oil?

    My truck is due for an oil change fairly soon and I've used Mobil 1 Synthetic since I've owned it. It now has 205,000km (127,000mi) on it and I was thinking of switching to dino oil. More specifically, Castrol GTX. I've heard wonderful things about it's sludge cleaning capabilities and dependability. On top of the $30 savings it would give me, I was thinking it might be better for a higher mileage engine like mine.

    Is there any benefit to staying with Mobil 1 or going to Castrol or is it all the same?

    2004 Silverado LS 5.3L Z71 Crew Cab
    260,000+ km

  2. #2


    Well you got over 205,000 km on Mobil 1 and its still running. If you changed the Mobil 1 when recommended then you shouldn't have any sludge in the motor. I'd stick with the Mobil 1.

    2005 Chevy Silverado Z71 Crew Cab
    6" Skyjacker lift w/Edlebrock dual front remote resoviour shocks, single rear remote. Rancho skid-plate.
    17" x 9" M/T Classic Lock Wheels, 35" BFG A/T or M/T tires
    4.10 PercisionGears w/factory locker, T/A Performance rear-end cover
    Banks CAI intake, ported throttlebody, JBA coated headers, over-sized Magnaflow cats, Magnaflow cat back exhaust, Diablo tuned
    B&M aluminum deep transmission pan
    Warn brush guard w/Warn 9.5 XP winch, PIAA bulbs, Line-X bedliner, AWS Black tool chest, Extang tonneau cover
    Weather Tech floor mats
    Cover-Craft seat covers
    Dash mat cover
    Formula One window tint
    One black Lab in rear seat.

  3. #3
    Sr. Apprentice
    Join Date
    Nov 2011
    Shady Spring, WV


    I agree with staying with mobil1. If you switch they recommend you stay will the same weight. We were always told it is okay to switch as long as you keep the same weight.

  4. #4


    I have actually been using either Mobile 1 or Royale Purple.

    That is until now.

    Just switched to Amsoil, cause it was almost $2 a qt cheaper.

    Hoping it was a worth while risk.

    We shall see...
    Pavement sucks... :grrrrrr:

    1994 K1500 4x4 Ext. Cab
    PCM chip and Xenon 8000k bulbs bored over .050"
    balanced Crank, 10:1 compression
    Flat top pistons,cam,ported heads
    Option Racing Cold Air Intake
    Holley Throttle Body Spacer
    Accell Igition, 45kv coil
    FloTech Headers, no CATs, dual exhuast
    Goodyear Silent Armor A/T 305/70-16
    Pioneer SupertunerIII CD USB Bluetooth
    Kicker ZX200.2 ZX Amp
    Kicker Audio COMP 10" Subwoofer

  5. #5


    I would stick with Mobile 1 or any full synthetic oil. I wouldn't go to dino oil. All motor oil has to pass government standards and tests, others just go above and beyond. I use full synthetic Castrol. You shouldn't have to worry about sludge. Back in high school auto class I worked on a teachers (female) car. I had to do intake gaskets. It was the dirtiest sludgiest engine I've ever worked on to this day. I asked her and she rarely had her oil changed, and her drive to school was less than five minutes. In Ohio with the winters the engine never warmed up to get rid of the condinsation.
    "If it ain't one thing, it's a mother******g nother"

  6. #6


    I would stick with what has worked for you til this point. The old saying if it aint broke don't fix it comes to mind.

  7. #7


    I have been using the normal (not full synthetic) Castrol GTX 5w-30 in my tuck and I have the opposite question...... I was looking to go full synthetic. Either Castol full synthetic or the Mobil 1 and was not sure if I should do it. I am sitting at 206k on the engine.

  8. #8
    Sr. Apprentice
    Join Date
    Jan 2012
    Sault Ste. Marie, Ontario Canada


    Synthetic oils will remove sludge build-up on internals and around gaskets. Synthetics usually get blamed for oil leaks, when in fact all it is doing is showing where there has always been a leak that has been plugged by sludge. At 206K miles on that engine I'd recommend you keep using conventional dino oil. Its a little too late in the game to convert over to synthetic because it's likely to spring a few leaks as the synthetic does its job.

    If you want to play it safe just switch to a high milage conventional oil.

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