How Reliable is GXP verus Standard 3800?

**njgp** · 04-06-2017

How is the reliability of the GXP versus the standard 3800 engine? I have an 2004 base model GP that I've been very happy with. Thinking of upgrading to an 07 or 08 GXP but I'm not familiar with the reliability of the GXP versus a standard 3800 engine.

**Fivefingerdeathpunch** · 04-06-2017

If the AFM/DoD was out of the question, they are just as reliable. The LS motor is very strong and just as bullet proof as the 3800 is with thousands of these engines running for tons of miles trouble free.

The downfall is still the transmission.

**njgp** · 04-06-2017

What is the "AFM/DoD"?

**Below Average Joe** · 04-06-2017

Active fuel management and displacement on demand iirc

**Fivefingerdeathpunch** · 04-06-2017

They are the same things, average joe is correct on what they mean.

The LS4 has AFM/DoD that shuts down 4 cylinders at cruising speeds, being a early design still they are pretty prone to burning oil and having a possible DoD lifter failure. If that was either shut off or removed completetly the engine will burn far less oil or even none if it never did in the first place. If it was completely removed and was like a standard 5.3 LS it would be rock solid.

**njgp** · 04-07-2017

What do you mean "ths downfall is still the trasmission". Do they have problems?

**nox** · 04-07-2017

The 4t65e(-hd) is garbage. Pure garbage. It was a weak design that was a coinflip for longevity. Some people lasted forever stock.

The GXP shreds stock transmissions. A combination of early fluid having a low breakdown temperature ~200F and weaker internals was a recipe for disaster. Some cars lost transmission 1 as low as 20k miles, some as high as 70. GM decided to put a transmission designed to daily drive a 195/250 HP/TQ motor and strapped it on a 305 HP/TQ motor. Couple the above with the heat soak from an LS and its easy to see why they fail.

If you have the money, a Triple Edge Performance transmission should be acquired sooner than later. A good one is 2000ish if you don't plan on heavy modding. I'd advise anyone buying a GXP to ask if it has a TEP transmission and if not add close to 2500 to the price at minimum to get one.

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**Below Average Joe** · 04-07-2017

If you don't have the cash right away if you do purchase a GXP, a transmission cooler and a fluid change are a must and even a shift kit. Nox is right about TEP transmissions. They are pricey, but are worth is. Here is the link http://www.tripleedgeperformance.com/

**njgp** · 04-08-2017

Is it also true you should only use premium gas in the GXP? If so, between the transmission blowing up and having to premium gas for a daily driver the regular 3800 engine sounds A LOT more reliable and affordable.

**Scottydoggs** · 04-08-2017

if you drive a supercharged 3800, guess what, you need to run super and the tranny still blows up, im on #2 in 6 years now.

**SgtMarshal** · 04-08-2017

I have a 2008 Grand Prix GXP and a 2001 Grand Prix GTP. The 2001 is substantially faster because I have done a lot of work to it, but the 2008 is nice. the 2008 rides so much smoother and is so much more comfortable. I don't plan on modding it much because it already has plenty of power. I daily drive my 2008 and the 2001 sits in the garage. I bought the 2008 just after Christmas last year and since then I have changed the ac compressor because it was noisy, 2 motor mounts, and the harmonic balancer. I also changed 2 rear speakers because one of the monsoon speakers was blown. the only other thing I need to fix at this point is something in the steering because it is just a tiny bit loose sometimes.

I say all this as an example of stuff that wears out and/or breaks. My 2001 all had similar stuff break. I would not recommend running anything less than premium in both vehicles.

**njgp** · 04-08-2017

So sounds like for reliability and affordability stick with the non-super charged 3800 engine.

**Scottydoggs** · 04-08-2017

truth is the na engines got their own issues, and they also blow up the tranny. these trannys are the weak link. the 3800 is a top 10 gm best build ever engine. so we do have that going for us.

a supercharged car is much more fun tho. mods are rather reasonable at this point too. due to its a dying platform these days.

**SgtMarshal** · 04-08-2017

even the naturally aspirated 3800 has problems on occasion. you just have to pick your poison. I really like my 2008 GXP.

**Below Average Joe** · 04-08-2017

They are right about na 3800's having issues. My 2005 GT which is na ate through a transmission after about 105k or so. Now I'm running a TEP trans with a cooler and have to worry no longer. I feel that if you take care of your stuff, the reliability will come along with it. If you drive it like you stole it all of the time, then expect things to wear out and break sooner.