Do I have a DTS lemon?

Just bought a used 2010 DTS livery car (airport, etc.). Cold engine sounds like a diesel or when an engine is out of oil. At normal operating temp, the engine purrs like a kitten. I use 93 octane.

Tell me the noise is normal for a Norstar engine when cold, please.

Since we can’t hear your engine, your best bet is to go to another Cadillac dealer, test drive another car, and see if it makes the same noises when ice cold.

If it doesn’t, then yours is abnormal.
If it does, then its probably a noise associated with the fuel injectors that you are hearing.

My Altima makes a lot more noise when its ice cold than it does when its fully warmed up.
So far, 50k miles, and still running along flawlessly.


It sounds as if piston slap may be your problem. Various Northstar engines and many GM engines over the last decade or two are known for this. Comparing it to another cold engine of the same model may not be useful, because not every engine gets it. Usually it’s just annoying and doesn’t cause any real problem. But it’s kind of sad that this isn’t resolved yet in 2010.

So to sum up: The noise may be ‘normal’ for this motor. Google “northstar piston slap” if you’re bored.


It would be interesting to know how many miles are on this thing and how it was driven and maintained. I’ve seen some pics of an '09 Northstar that was sludged beyond belief so the possibility exists that this could be valve lifter clatter.
Also agree that it could be piston slap, which would be preferable over valve clatter.

Thanks for your response. It has 23k miles, driven for 9 mos and a record of i oil change on carfax.

It should have had at least 3 oil changes by now. Is there any way to find out how many it’s had? Did you buy it from a dealer or private party?

I’m in agreement with Mr. Sanders that this car should have had 3 oil changes, or more, by now. This is all assuming that Carfax, which is notoriously incorrect much of the time, is even right about the one oil change being shown.
Pretty conscientious of someone to report a single oil change to CF.

Over the years I’ve seen several 20-30k miles engines with oil sludge problems and one of the absolute worst was a 25k miles Subaru that was sludged so badly the engine was not even rebuildable. The amusing part (at least to me) was that when the drain plug was removed nothing would run out and when the pan was removed a long screwdriver that was inserted vertically into the engine oil would not fall over.
I could have hung a hat on it with no problem.

I believe I would change the oil and while the drain plug is out you might take a length of wire (coat hanger, etc.) coil a small loop on one end, and insert it into the drain plug opening. Fish it around a bit and check the loop for sludge when removed. There really should be none on a 23k miles engine, but…