Problems with my 05 2.8L CTS and Suggestions for Increasing Longevity

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Cadillac CTS First Generation Forum - 2003 - 2007 Discussion, Problems with my 05 2.8L CTS and Suggestions for Increasing Longevity in Cadillac CTS Coupe, Sport Sedan and Sport Wagon Forums; Howdy, this is my first post on Cadillac Forums. I want to run over some details about the current state ...
  1. #1
    micchickenburger is offline Cadillac Owners Member
    Automobile(s): 2005 CTS 2.8L
    Join Date
    May 2013

    Problems with my 05 2.8L CTS and Suggestions for Increasing Longevity

    Howdy, this is my first post on Cadillac Forums.

    I want to run over some details about the current state of my vehicle in hopes that I can receive advice on what to address, as well as how to ensure vehicle longevity.

    I bought my CTS at 28k miles and was burning about a quart of oil every four to six thousand miles, which I understand is 'normal' for these engines. However, I'm now >150k miles and I'm burning a quart every 500 miles or so.

    Last summer I replaced my air box with a K&N cold air intake because I do road trips often and I previously was having issues with not having enough power at elevations greater than ten thousand feet. I wanted to maximize compression by increasing airflow and by increasing the amount of air being drawn into the engine (colder air is denser, etc.) so I could enjoy driving through the Rockies in the early fall. While installing the intake, I noticed about a half a quart of oil in the intake plenum. I don't understand how that could be.

    Yesterday I replaced my spark plugs (second time in 150k miles) because I was having engine roughness and occasional misfires (though none would ever log--I would just see a flashing Check Engine light that wouldn't stick.) When removing the intake manifold, I found no oil at all (keep in mind this is 9 months after replacing the intake assembly) and found no issues with the two disparate manifold gaskets. I replaced the gaskets anyway when replacing the spark plugs. Engine feels much nicer now.

    So, what's happening to my oil? I believe it's burning because I see no leaks and I see no oil residue anywhere in the engine bay. Thoughts?

    As an aside, I apologize if I've fumbled some terminology. I'm more familiar with aircraft systems than automobiles, and in either case I'm no mechanic.


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  3. #2
    DopeEffect's Avatar
    DopeEffect is offline Cadillac Owners Enthusiast
    Automobile(s): 2006 3.6L CTS, Hotchkis Sway Bars, FE2
    Join Date
    Jul 2012
    Dallas, TX

    Re: Problems with my 05 2.8L CTS and Suggestions for Increasing Longevity

    Oil in the intake plenum is pretty normal for our cars. One thing you could do to prevent that from happening again (even with your K&N CAI) is by installing an revxtreme catch can. A lot of members on the forum have done this mod and it makes a phenomenal difference. You will also get a first hand look at how much oil would be going into your intake plenum if the catch can weren't there.

    From the pics I've seen it's a good amount of oil so you'll be helping out your valves quite a bit. Since you have a 2.8, you have timing chains (sorry). Oil consumption on that level goes hand in hand with the timing chains wearing out. If you're burning that much oil, might want to check your oil filter/oil next time you change it. Actually cut the old filter open and look for chunks of plastic and metal shavings/bits. The plastic is from the guides that the chains run along. The shavings are from the chain. If you see copious amounts you might want to look into getting them changed. Be prepared, it's expensive unless you do it yourself.

    Idk if you've ever seafoamed your vehicle but doing so can help your engine out quite a bit. There is a how to guide in the DIY thread.

    Since you have a CAI you should look into maybe getting a vmax iceolator. It's essentially a spacer between your throttle body and intake manifold (what sits directly on top of the heads), that or it sits in between your intake manifold and your heads. Helps your throttle body run at a much lower temp. People have posted pictures of the temp change before and after. It's gives you at least a 30 degree difference if not more.

    Besides changing your oil every 3k and running some seafoam in your oil, fuel, and brake booster line every 10-15k theres not much else I know that can increase the longevity of the engine.

    Hope some of this info helps.

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