Some questions about oil/ filters, coolant elbows, S/C coupler replacement

**mngtp** · 11-14-2013

We have a '99 Grand Prix GTP with 225,xxx miles on it. We live in Minnesota. I have a list of things I need to get done on the car before it gets too cold out. So I have a few questions:

1.) I need to replace the coolant elbows, one is cracked. Should I replace them with the aluminum or plastic elbows? From my searching I have found mixed opinions. Im leaning towards the aluminum ones so I dont need to change them again anytime soon.

2.) How many gallons of coolant will I need? I think I read 3 gallons somewhere. Im going to be using the green stuff. And I want to flush out the radiator and engine with the garden hose. The engine block itself holds one correct? If Im right (it doesnt happen too often according to my wife lol), I will need 1 gallon of the pre-mixed 50/50 and 1 gallon of the straight coolant if the block holds of fluid (water) after I flush it out. If I drop the lower radiator hose, will that get more water out of the engine block?

3.) I know a lot of you guys use the lower rediator hose to drain the coolant. The tabs on the actual drain plug broke off, Im wondering how hard it is to raplace the drain plug? I was thinking about replacing it since the radiator is going to be empty anyway.

4.) What brand oil and oil filters does everone recommend? I have been using Valvoline conventional and FRAM. I dont have a NAPA near me but there is an O'reilly just a few blocks away from our house. For the most part the general opinion is that FRAM isnt good and that is what I have been using since its cheap. O'reily carries Microgaurd, WIX, BOSCH, AC DELCO. At least these are the ones in our price range ($6 or less). Should I switch to high mileage, sythetic, sytheic blend, or is the conventional oil ok? A side note, the car does leak a little oil (a little less than a quart every 3,000 miles) from the oil pan gasket and from what I have read, the sub frame needs to be dropped to replace it. Correct?

5.) Is it difficult to change to change the S/C coupler? It sounds like there are marbles in the S/C snout. Is there any other places to get the S/C oil besides the stealership or W-body online store?

I just want to make sure I am doing everything I can maintenance wise to take care of the car. Its our only car right now. So its our work commuter, grociery getter, family hauler (we have 3 kids). But when tax time comes we want to get a second car and this GP will be my work commuter. Our price range will probably be $5000 or less. She wanted a v6 Charger. But she is coming aroound to the '04+ Grand Prix's. But she said it has to be supercharged.

Thank you for taking the time to read my post. Please feel free to leave any tips or suggestions. I can use all of the help I can get.

Max Cook · 11-14-2013

1. Aluminum
4. Any filter but fram is fine. Fram is the worst by far. I use mobil 1 or KN filters. Oil is all preference. As long as you change it enough its not a big deal but I always stick to mobil 1 10w30 personally. And yes the oil pan is a ***** and you do have to drop the subframe to do it.
5. Its very easy and there are multiple write ups on how to do it. ZZP also sells supercharger oil...

**TLSheff** · 11-14-2013

Good questions sir.

1) Alot people use the Aluminum ones as the plastic ones DO break far more often than they should. But with regard to that, consider that they ARE the weak link in the coolant flow system. Should they not be able to break and you get a pressure spike for whatever reason from the water pump (which has happened before) and the elbows don't break, you tend to blow a LIM gasket. So rather than replacing $10 worth of eblows and a $15 gallon of coolant, you get a $200 LIM gasket job to play with. Now that is the worst that will happen, but just saying, food for thought. The plastic ones are cheap and take maybe an hour of time to replace with hand tools.

2) Last time I flushed the coolant completely I only needed 2 gallons to get it back to a good mixture. I would think 3 would WAY over do it, unless you spill alot, then by all means. I would flush it all, then let the water drain out, put it all back together, add 1 gallon straight then the 50/50 as needed. As the water level left in the motor and heater core will add to the gallon of straight coolant and mix for a proper 50/50. Worked for me anyways.

3) If the tabs are broken off, and you can't get a pair of vice grips on it loosen it, you'd have to drill and extract it out with an extractor bolt. But its not really needed, just up to you. Most use the lower hose because its easiest to do and works every time.

4) I use Mobil1 5w30 Synthetic and an AcDelco filter usually, but WIX is my personal favorite, one of the best you can buy for cheap filters. Oil is all preference on these old motors, they take anything lol, but if you start with synthetic, stay with synthetic, don't jump around. Yes the cradle needs to be lowered a little, or the motor needs to be lifted a little to get the pan off to re-seal it. Its a pain to do, but worth it if you have a big leak.

5) http://www3.sympatico.ca/aepa/blowerinstall.html <--- How to with pics. Use an Anaerobic Gasket Maker type sealant to reseal the snout so you don't have leaks, and you can use GM fluid if a local dealer sells it, or Mobil1 5x30 oil otherwise. You just have to change out the oil every / every other oil change with the motor oil. It doesn't last near as long, but if you can't get it or don't want to order it, makes for a simple replacement.

Hope this helps, Good luck!

**stocker** · 11-14-2013

Hello fellow Minnesotan!

I think the other replies have answered most of your questions. I would add that if you've already been running conventional I would say you can continue running conventional. I've heard switching to synthetic can cause more leaks to appear - since you already have a moderate leak, I'd say just stick with conventional and keep fresh oil in it.

Best of luck and hope the GP treats you well

**mngtp** · 11-15-2013

TLSheff, I really like your GP. Anyway, you bring up a good point about the aluminum vs plastic elbows. Maybe I might go with the plastic ones for now. if they break, well then I will know how to change them. Better safe than sorry.

Does anyone have a part number for the plastic coolant elbows?

I can get a vice grips on it. Im just wondering if the plug just pulls all of the way out or if its a big fight to get the old plug out and get the new plug in.

Has anyone else used Mobil 1 5wx30 as a substatute for actual S/C oil? Can the two mix if there is a little of either in the snout or is it important that the dont mix? How much fluid does the snout hold? Is it 8oz's? I cant remember, I just remember it takes two bottle of S/C oil. Can someone tell me if its normal for some S/C oil to be lost after a while? If so, where does the missing fluid go?

Stocker, good to see another Minnesotan on here. I will most likely stick with conventional as I have heard simular thing about switching. I remember reading that conventional oil helps swell gaskets or something. I usually try to keep 1 quart of oil in the trunk and another in the garage, just in case.

Thank you all for the replies and suggestions. Most of my original questions have been anwered. I just have the few new questions to be answered

**nik12937** · 11-15-2013

You have a rad cap rated to release at a certain pressure, if aluminum elbows cause a LIM gasket failure, you have bigger problems.

**mngtp** · 11-15-2013

Another good point. Is there a way to tell if the LIM has been replaced before? We have owned this car for 3 years now and we havent replaced it. We bought it with 160,xxx miles on it.

I heard the HELP! brand plastic elbows are junk. Is that right?

Again, I really appreciate the help from everyone.

**REDCRAPGP** · 11-15-2013

Look at where the lim meets the heads...there's a gastric if it's plastic it's plastic if it's silver well then it's aluminum. Stick with the dorman aluminum arms the plastic ones are junk.

Max Cook · 11-15-2013

Don't use anything but GM supercharger oil in your supercharger. Unless its some kind of emergency situation or something like that. Otherwise only GM supercharger oil..

**TLSheff** · 11-15-2013

In regards to the Rad Cap releasing pressure, they DO fail over time and if it fails and there is a pressure spike... boom, elbows bust. Seen it happen before. The elbows are easy to change, you just have to make sure when you get the old ones out you get it all cleaned up or there is a potential for a leak.

GM# for the elbows are #24503243 - $12.97 retail & #12565082 - $3.98 retail. Any local GM dealer should keep several on hand as they get replaced ALOT.

I personally use the Mobil1 5w30 in the snout and know several others who use it in their. It does take 8 oz and IF you can get it from a local dealer you can, but if not (like me, no local dealership sells it and I don't want to order a case), you CAN use it without problems. Been 30,000 miles so far without issue, just change regularly. Also as with any oil, after so long it will start to break down and that is why it shows to be low. It also goes in clear, but comes out dark brown and stanky after 75,000+ miles.

**Primal** · 11-16-2013

Regarding the radiator drain plug replacement, there are part numbers for stock and aftermarket in this thread: http://www.grandprixforums.net/showthread.php?t=84181

Adam

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