Couple of basic maintenance Q's


Just bought an '00 Olds Sihouette; 103K; well maintained & I have all of the records.

Q1: Antifreeze. As a GM Dex-Cool is recommended. When the intake manifold gaskets were done (in the 93K range) the receipt specifies that Peak Global was installed. I want to clean the coolant reservoir and have some Dex, but no Peak “global”. Can I refill the reservoir w/ Dex or should I go get a gallon of the Peak global? Cold, the reservoir takes maybe a quart or less. The coolant has only about 10K on it. Is there any reason I should flush out the whole thing and go back to Dex - I’ve actually heard that Dex might be related to the intake manifold gasket problems on GMs.

2) GM “oil life system” - I’m about to change the oil and there is apparently some sensor that will turn on a “change oil” light when it detects that the oil needs to be changed. Manual says it doesn’t go by miles by by “engine revolutions and engine operating temperature.” I don’t need a machine to tell me when to change the oil - I’ll just do it every 3K or so. But does anyone know - if the light isn’t on and I change the oil do I still need to reset this system? And will the reset really reset it if the light hasn’t been triggered yet? I don’t want that stupid thing confusing me in the future.



(1) I don’t know much about Peak “Global”, so I’ll defer this one to someone more familiar with the product.

(2) yes, you still need to reset the system. It has no way of knowing that you’ve changed the oil. It doesn;t actually measure anything about the oil, just measures engine use since the last time the system was reset.


Peak Global Lifetime is just fine. While I don’t consider any coolant to be “life time”, it is an all makes, all models antifreeze fill and I would leave it in for 30K miles or three years. Not a big fan of Dexcool, but having no knowledge of anyone who had problems with using Dexcool, I would not go back to it. Get a jug of Global 50/50 mix to do minor top offs. Note that if you have to do a lot of topping off of antifreeze, you may still have an undiagnosed coolant loss issue to deal with. I literally put no new antifreeze in any of my cars between 30K mile change outs, so if you have to top off more than just occasionally, be aware of your possible coolant loss issues.

Here are all the specs Peak Global Lifetime meets, so it sounds like a keeper:

ANFOR 15-601
BS 6580 (British Standard)
Chrysler MS7170
Chrysler MS9769
Ford ESE-M97B44-A
Ford WSS-M97B44-D
Ford WSS-M97B51-A1
FVV HEFT R443 (Germany)
GM 1825M
GM 6277M (DEX-COOL? Spec)
JASO M325 (Japan)
JIS K 2234 (Japan)
SAE J1034
Mercedes Benz DBL 7700


I have a 2000 Silo too and after the intake manifold gasket (new revised gasket kit, Feb/03) was changed (Immediately after the leak started), oil and filter replaced, the remainder of the old Dexcool was flushed out and new Dexcool was installed. That was in Sept/04.

I too, change the oil/filter every 3K miles and coolant (drain/refill only) every three years and have had no problems since. My independent tech resets the oil life monitor after every oil change.

I was beginning to wonder if it even worked, so I let the time elapse and sure enough, the message came on.

I’ve read that a lot of owners have opted to replace the Cexcool with the old standard green coolant.

There’s absolutely nothing wrong with that except you MUST make certain all the Dexcool has been removed.

Dexcool doesn’t mix well with other coolants/properties.


Thanks much for that. Just looking at the receipts I now don’t think the system was flushed or even fully emptied when the intake was done. I think that a basic drain was done and replenished with the Peak global - which is one of those that is supposed to be compatible with any type of coolant. The current coolant is orange. Based on the last time it was actually flushed, and my questions about it, I think I’m just going to go ahead and flush it out.

How does one recognize it if the intake starts to leak? Is missing coolant the surest tip off? I’m a little paranoid now as I don’t know if the new gasket kit was used (though it should have been as it was done in August of '07).


Frankly unless you drive less than 10,000 miles a year or drive mostly trips less than a mile or two, you really don’t need to change the oil that often. Back in the 60’s when I learned to drive, that made sense, but cars and oils are far different than then. Modern oils and cars do just fine with the extended oil changes recommended by the manufacturer. There is even some evidence that changing oil that often may be bad for the engine.

Back in the old days you would find cars in the junk yards that were put there due to oil related problems.  Today you would be very hard put to find a car in a recycle yard that was put there due to an oil related problem, other than owner neglect by letting the oil go too low or not change it for over 100,000 miles (Don't laugh I had a co-worker who was having problems at 100,000 miles and he had never changed the oil.