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256K views 511 replies 289 participants last post by  jmlcaton 
#1 ·
I have a 97 DeVille with 107400 original miles, which I know is not much compared to some of you. To figure out whether or not I can expect much more out of this engine, I would love to see how many of you have Northstars with higher mileage. If your engine is not the original, please let us know. Any major problems along the way would also be helpful, with mileages. I think that a thread like this could really help some of us anticipate problems and estimate the life of our engines!

Thanks,
Jim

My entry:
107400 miles original
no known major problems
now leaks a little oil (began around 100k)
 
#383 ·
Holy Moly, Are all those original miles? If so, that's the highest I've heard of anywhere on the planet! Any tips? Certain oil interval or brand? And do you really believe in the old proverbial saying, "A red line a day keeps the repair aways!" I'd really like to know what are the major stuff you needed to repair or replace.

jackster
 
#380 ·
182K on my '97 STS.
Up to 6 months ago it was all untouched power train, since the engine was pulled 3 times and the transmission was replaced twice.
It all started with a winding noise when shifting until eventually it was slipping and winding all the time.
Finally the 3-rd time when the engine was removed the transmission was replaced with a new GM unit and hope for the best.
Ah...and since I did not wanted to go again trough another engine removal I decided to stud the engine for absolutely no reason, it was holding just fine but is safer now. The bottom end was resealed and the timing chains and tensioners replaced (one of the tensioners was worn all the way to the metal). That's about the only thing worth to be mentioned with the condition of the engine.
Engine awesome, transmission pretty disappointed as it lasted only 175K and it was really well taken care of (I mean REALLY well, never ever abused, fluid/filters changed 3 times).
 
#393 ·
Ok - I just found this thread and joined the forum just so I can reply to this. My 2004 deville has 217,700 on it currently and I do NOT consider this high at all. The day I bought it with 62k on it I fully intended on taking it to somewhere between 350k and 400k before selling it still running good. EVERYTHING with a northstar has to do with proper maintenance. I use Mobile 1 Extended performance 15k oil and change it every 6k to 8k miles. Don't use fram paper oil filters - use the supertech from walmart or the Mobile 1 filter - both are very comparable actually as they are fabric, high-flow filters. Switch to the K&N air filter, change your fuel filter every 30k to 50k miles, flush your anti-freeze/coolant every 60k miles or so but IMMEDIATELY get rid of the Dex-cool (that's first priority - did it at the dealership day I bought mine and replaced with Prestone Global). Change your plugs using original iridium plugs every 60k to 75k miles. At 9 years old and nearly 220k miles my car is literally as smooth as it was the day I bought it and looks new in and out. I can look down into the oil fill and the engine look as clean as new inside. There should be absolutely no reason to not get another 150k out of her. Take care of your cadillacs and you can drive them about as long as you'd like. I still get the same gas mileage that I did when I bought it (which with the air filter and fluids listed above is 31 mpg highway at 70 mph). I floor it routinely to keep the carbon out of it as well about once every 2 weeks taking it up to 90 or so very briefly (from current highway speed - never from stop or lower spead as this is aweful for a car). Also, the use of a fuel injector cleaner is extremely helpful - I use Lucas Oil for this every 3rd fill-up and only use good quality fuels. I also strongly recommend changing your transmission fluid and steering fluid every 60k to 70k miles also and during this I add 2 quarts of lucas trans fluid (normally 1 but the pan on this transmission is an 18 quart pan). The 4t80e transmission will ALSO drive as long as you want to drive it as long as you change the fluids and treat it well. I should point out that this is the routine I use on all of our vehicles and we almost NEVER have any car problems and I strongly recommend it. I think that Amsoil would likely be as good or better for any of these fluids, but I've had a working process with easy accessability to the ones I use so I've stayed with the ones I currently use. I LOVE cadillacs - have all of my life, grew up with them and have seen even models that were considered garbage run fantastic for years and years (mid-80's 4.1 - never had issues with them) when maintianed well.
 
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