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Quention re: Hemi 300 Service

My 2006 Crysler Hemi 300C has 63,500 miles and is running great! Dealership where I have 5,000-mi oil and filter change done is “hard-selling” me to have the following service done, starting immediately, in this order: Tune-up & Fuel Svc for $340; Transmission $ Differential for $280; and finally Power Steering Flush for $95. IS ANY OF THIS NECESSARY now? Or am I being coerced into forking out big bucks just to be “safe”?

The owner’s manual will tell when to service the transmission and differential. The other stuff is pure profit.

Assuming you have reviewed the manual and none of these items are in the recommended service at around 60k, I’d do none of them.
Tune-up & Fuel Svc for $340 (no, only thing to ‘tune up’ is new plugs, if called for in the manual)
Transmission $ Differential for $280 (If you have never changed the transmission fluid it might be a good time (what’s manual say) but I would do nothing to the diff besides check level, unless manual calls for it)
Power Steering Flush for $95 (nope)

There’s really no such thing as tune-up anymore. That word is sort of a misnomer.

However, it very well may need a maintenance service of sorts. If the car has the original spark plugs in it then they’re past due no matter what the owners manual states.
Same goes for the air/fuel filters. If this has not been done then you’re neglecting your car.
Ditto for servicing the PCV valve.

Since I assume the transmssion is an automatic it should have the fluid changed; and it should have been changed about 30k miles back.
The power steering flush is debateable. Is it absolutely necessary? No. Is it beneficial? Yes, to some extent.

The purpose of these things is to try and head a problem off rather ignore something until a fault occurs and then scramble wildly trying to cure it.
A transmission is the best example. Many never change the fluid no matter the driving conditions and then when a problem occurs at a 100k miles or whatever they often wind up on this board wondering if there’s a Miracle In A Can that can save the unit.

Thanx, mcparadise… am on right track with your and others replies!

Thanx, texases… am on right track with your and others replies!

Thanx, ok4450! So the theory that spark plugs do not need replacing if I am still getting good mileage and have no “knocking” is incorrect? I should replace 'em regardless?

The replacement interval in the service schedule is probably something around 100K miles. However, if you leave them in that long you risk having them corrode in place, which could result in stripped threads in the cylinder heads.

The problem with leaving plugs in too long is because of 2 reasons.
One is that subtle misfires may develop which leads to a slight loss of performance and fuel mileage. This may not even be noticeable to the driver and may not even set the CEL off but it’s there and can often be noticed on an oscilloscope though.
Two is NYBo’s comment about those plugs seizing in place; at which point the price of changing those plugs just went way up. There’s been multiple posts on this board about this occurrence including some references to replacing cylinder heads.

Back in the mid 80s it seems that many car makers went on this tear of “let’s make our cars appear to be more maintenance free” by delaying the very services they used to highly recommend be done. Every car maker and every area is affected.
Consider Honda’s recommendation about not inspecting valve lash until well over a 100k miles. While odds are most Honda owners won’t have a problem with failing to do this a percentage of them are going to be facing a large repair bill for having not done it.

Same thing with fuel filters. It only takes one tank of contaminated fuel to semi-clog a filter and this in turn shortens the fuel pump life even though the car may apparently run fine. I’ve seen cars towed in with less than a 1000k miles on them due to this problem and it happened to me about 2 years ago.
Before taking an out of state trip I serviced my Lincoln as I always do and noticed the less than 15k miles filter was pretty contaminated even though the car ran fine.
On the trip I made half a dozen comments to my wife about the fuel pump giving out and sure enough; after a 1500 mile trip and being only 20 miles from home on a very bad stormy night the pump dropped dead.

Yes, and that engine has 16 spark plugs to boot. Some of which are a swine to get to. Anything past 60k on the plugs and you’re in danger of fusing them in.
To me, it’s money well spent.

The only thing out of this I really see is the trans service. Your trans should have just had its second service. Drop pan, change filter, and refill. Service an automatic every 25-30k miles. Especially this trans, its expensive. I have the same one in my 06 HEMI Charger. Its a 5 speed automatic. TAKE CARE OF IT!!, you dont want to have to buy another one. I dont give a rats tail end what the owners manual says, SERVICE AN AUTOMATIC EVERY 25-30K. This advice comes from 25 years on a transmission rebuilding bench. You might need a tune up depending on what the plugs look like, fuel service, I’d pass, Differential, pass on that too. Power steering flush, no… Hope this helps you.


I’m going against the grain here on the spark plugs. If your owners manual says that they are good for 100-120k miles, they are good for that. They wont “fuse” or bond with the heads. That was a problem with the early 100,000 mile plugs, but they now put a coating on them that prevents that. I just changed a set at 117k miles, they came out easy, no problem.

I do concur with transman, he knows stuff about trannys.

Older Chryslers reccomended the plugs be changed about 35k miles. I don’t imagine that has changed much.

There’s also another point to be made about leaving plugs in for too long. Note the number of failed coil/coil pack/coil on plug complaints and ponder the reason behind those failures. It’s most likely due to chronic sublte or not so subtle plug misfire.

Coils have to work a bit harder than they did in the old days. Way back when many spark plugs were gapped at .025-.030 of a an inch. Later models often gap at .045-.055 and even over .060 in some cases.
The wider the gap the more the coil is asked to do. Throw in even a subtle, not noticeable misfire over the long term and the coil has to step up even more which means it, or them, will have a shortened life.

As to other maintenance items, my son just moved back to OK recently and we serviced the new '07 Dodge Caliber he bought last year. With about 24k miles on it (and running fine) the fuel filter was partially clogged and the air filter was absolutely filthy.
The recommended interval for plug replacement on this vehicle is at 30k miles.