Just got a 03 Grand Prix GT

**Lucid Violence** · 08-17-2009

It has 70,000 miles on her. It's black and has a sun roof. Unfortunately its a 4 door but ill get over it

. It's a one owner car mostly highway miles, now I know lots of people say that about the car they are selling but being this salesmen was my mother I think i can trust her

.

So right of the bat I want to flush the tranny and put on a trans cooler. I have an auxiliary one sitting in my basement that I want to put on after the fluid flows trough the radiator cooler, is that the most desirable way to have it? Wheres the best place on the radiator to mount it? So while I'm at it I'm going to replace the filter. Are the one from Parts America or RockAuto okay or do I want to find the GM one from a dealer? And what fluid will be best to use and how much of it do I need?

The car comes with DexCool in it. Now some people say its junk and should be flushed out for the old green stuff, is that true? How I normaly flush a radiator is to take out the thermostat and keep filling and draining it with distilled water till its clean, then top off with coolant. Would this be okay for the switch?

I also want to do a general tune up. Besides oil and filter, air filter, fuel filter, PVC valve, spark plug and wires what else should I check or replace?

Now after all that I want to start my modification for handling and speed. My first thing I want to do is to put on the GMPP handling kit with rear strut tower brace. Now that should be a nice little improvement in its self but if I wanted to go to the next level it would be struts and springs right? I would like to go a bit lower but nothing extreme wanna keep it very street-able.

I'll end this here being I could go on and on with the questions. So any help to get me started would be great! Thanks

**rocafella2032** · 08-17-2009

Welcome, I also have an 03 gt.

**nault31** · 08-17-2009

Sorry I can't answer your first question.
Avoid the old green coolant, I just flushed my 98 GT with Prestone Extended Life coolant, it works for all makes and is certified by GM as a Dexcool replacement. I also changed the thermostat and the radiator cap ($13 at local dealer) since they were gunked up.

While I was at the dealer, they also found 2 active recalls, so I don't mind free service.

When changing the air filter, avoid the K&N oiled air filter, I bought one of those and it dirtied up my MAF sensor causing a P0171 code.

I would also buy one of these water slides and add a cabin filter:
http://www.grandprixforums.net/f73/w...-fix-6961.html
My local GM dealer had it for $3.60. Sorry I don't have the part #, it should be in the post. I went to autozone and had them type in the cabin filter for an 04 grand prix (I hear a buick regal also uses the same), so again sorry I don't have those part #'s off of the top of my head.

Speaking of water, I thouroughly inspect and test my sun roofs for leaks, just in case.

How are the brakes? An upgrade to keep in mind of you are modding for handling and speed.

And I've had a neighbor fork over a lot of money on towing and repair when a trailing arm broke, so the GMPP handling kit is a great idea, especially for a climate that deals with road salt.

**nault31** · 08-17-2009

And I forgot.. Polish/Wax and RainX
Maybe to be ready for winter as well, make sure the washer fluid is the winter blend to avoid freezing, or do what I do and get the RainX stuff that is an all season blend

**Thunderturd** · 08-18-2009

Clay bar then wax. Nault covered most of it. I would check over the brakes and the bushing that you pump full of grease on the shock, I can't remember the name of it X.X

**GP08** · 08-23-2009

Well, I have an 08, well, the car is still too new to have any issues yet, but, is that true about the dex cool? The GM cars kinda recommends the use of it, but if they are garbage?.....

**nault31** · 08-24-2009

I won't go as far as saying DexCool is garbage because while there are a number of reports and lawsuits and blah blah blah, I haven't seen hard evidence that all of that is caused by the coolant and not by contamination. I did find some of that brown sludge when I flushed my coolant, but then again, who knows what the previous owner of my car did.

I made the mistake of stating that the yellow prestone is a dexcool replacement, in fact it is the Prestone DEX-COOL Extended Life Antifreeze that is certified as DexCool spec..

However, straight from the Prestone site:
"Prestone® Extended Life Antifreeze/Coolant is compatible with ANY antifreeze/ coolant – regardless of color – for use in ALL makes and models of cars and light duty trucks."

So I trust the yellow stuff as a safe alternative to DexCool.

**matt5112** · 08-26-2009

Undercoating might be a worthwhile investment if the underbody is still clean and you're looking to make it last a while.

If you haven't already, don't bother replacing the air filter and look into a fenderwell intake. (Searching FWI on the forums here)

**nault31** · 08-27-2009

Fender Well Intake Mod

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