2000 Bravada

Hi all, I am new to AF and this is my first post here. I wish I would have found this place 8 days ago (before I bought my vehicle). I bought a 2000 Olds Bravada with 84k and I really like it, I just don't like all that I am reading about them. I am quite mechanically inclined and have taught myself everything I know by doing and reading, but I feel horribly inadequate in this case (because of all the electronic stuff).
The dealer gave me an invoice saying they had changed the oil, replaced the intake gaskets, replaced the lower ball joints and the thermostat.
After having a new vehicle inspection done and driving it for a week here are my questions:
1. My mechanic said I need the oil cooler lines replaced. While they are obviously leaking some (not any drops on the garage floor... yet) it seems, from what I've read on other posts, that I might not necessarily be any better for spending my hard earned $341.64+Tax+Shop Supplies. Any advice?
2. My mechanic also pointed out that my front crank seal is leaking too, adding another $150+Tax+Shop Supplies to the repair estimate. Advice here?
3. The day after I picked it up, I drove to an ice fishing tournament 7 hours away. Half way up there the check engine light came on. I was already half way and not experiencing any driving problems, so I continued. The light went off after stopping to fill up and came back on 30 minutes later. On the way back it didn't come on until 5 hours into the return trip. Since then, it hasn't come back on at all. Can I still get info from the computer if the light isn't on? Could this just be the change in gasoline? I don't know what the previous owner/dealer were using, but I use 89 octane.
4. When I turn hard left or hard right (forward or reverse) the vehicle shakes and there is a thump like sound. I have read it could be the transfer case going out or just the fluid needing to be changed, any validity to these?

Any help on any of these would be greatly appreciated... also any advise as to whether I should attempt any of these on my own or have a mechanic do them would be great too.

I look forward to making much smarter decisions now that I have some good people on my side!

A 2000 with only 84K? wow
For your front seal I'd try a bottle of auto-rx. It will not fix a mechanical problem but it will clean up any gunk that maybe impeding it effectiveness. It may also clear up your CEL but I would get those read anyway at a local auto parts and see what they are. It could be something very simply or......

Oil lines, I'd look under the vehicle and see exactly where it leaking before I go spending any money. It shouldn't be to bad of a job to replace, sounds like a DIY.

www.auto-rx.com

I'd change the transfer case fluid to the GM Autotrac II blue to address your thump.

I've had two sets of remote oil filter lines blow on me. Trust me, its better to do this as part of preventative maintanence than after the fact. When one of these lines blows you will lose all of your oil very quickly. I did the work myself. It's not a fun job. But it is worth eliminating the drips and the potential of engine failure.

You should be listening for crank bearing noise...if you're dealer replaced your intake gasket...anti-freeze may or may not have mixed with your oil. The dealer may have replaced gasket due to this being a common problem with this engine, as opposed to failure of the gasket. Sometimes bearing noise can take up to a week or more of driving to present itself after an intake gasket leak. Not trying to scare you. Just trying to inform you.

Hi all! First of all, let me thank you so much for your advice. I really appreciate it.

So, I talked to the dealer and he said that he did replace the transfer case fluid; it was red fluid he took out and blue he put in. That was a couple hundred miles ago and in the freakin cold winter, could that just take some time to work... or should the thump be instantly gone?

Redddog60, thanks for the advice, I am going to clean the lines and see how bad they are leaking. Also, what does crank bearing noise sound like compared to other bearing noises? The dealer said he replaced that intake gasket as preventative maintenance. If the seal is leaking, can I find out sooner by changing the oil? If that's what's happening, what long term consequences would that have?

Thank you all again for your help and advice!

If the dealer did indeed replace the intake gasket as part of preventative maintenance. You should have nothing to worry about.

As for your transfer case. It required over 300 miles of driving for mine to begin to loosen up. You may want to try changing the fluid one more time.

Redddog, thanks for your advice. I will change the fluid again this weekend.

I'll keep you all updated on how things turn out. Thanks again!

I'd change the lines myself. Had to replace the oil cooler lines going from the filter housing to the radiator. Auto part store wanted $40 for the lines. Still need to replace the ones going from the housing to the engine. Good luck.