1997 Tahoe with 100,000 miles....advice please.

[Chris B.]

I bought a buddys 97 2 door Tahoe this week. He is a BMW mechanic and has had no trouble with this truck. He said it has been more reliable then his BMW's. It has 100,000 miles on it and was on a diet of Castrol 5w30 conventional-5w40 it's whole life. I'm wondering if I should switch to Halvoline dino or do an Auto RX and put GC in it oe stick to the dino Castrol??? It is the Vortec 5.7 and runs smooth! Do you think the seals will leak if I go synthetic with this kind of mileage???

I have always used Synthetic but all my car have started on it early in their life.

Any advice on this engine is appreciated!!!! Thank you!

 

[Ugly3]

Why change a good thing?

 

[edvanp]

Personally, I think I'd do an ARX first then consider Castrol High Mileage or a good 5w40 (Shell ROTELLA® T or Delvo).

 

[dustyjoe1]

Castrol is not my favorite, but it has been known to be pretty good oil, in this case I'd probably stick with it...

 

[SteveD2]

quote:

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Originally posted by Ugly3:
Why change a good thing?

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I don't understand why people allways ask this. Why do so many people here run Amsoil oil with bypass filters? I'm sure they had a "good thing" with $.99 oil and Fram filters. Just because something worked doesn't mean it was a good thing. With only 100k, this engine should be in perfect working order with any oil, as long as it was changed frequently enough.

 

[haley10]

Maybe your buddy can fix you up with some of the good BMW Group III syn real cheap?? That's some pretty good stuff. Seems like a good match.

 

[Ugly3]

ZmOz - I don't understand why people allways ask this. Why do so many people here run Amsoil oil with bypass filters? I'm sure they had a "good thing" with $.99 oil and Fram filters. Just because something worked doesn't mean it was a good thing. With only 100k, this engine should be in perfect working order with any oil, as long as it was changed frequently enough.

People ask this because they see someone getting good to excellent results (as is this case) and feeling a compulsion to make it "better". "If it ain't broke, don't fix it" comes to mind. Secondly, very few people are running Amsoil synthetic oils and a bypass filter system, maybe less than 1% of the population. And finally, I agree that the use of most any API certified, proper SAE weight motor oil changed at a decent interval will serve the user well.

The data generally suggests that there is little difference in wear rates between brands of motor oil or between synthetic and conventional. I am not talking about some Hemi, roller camed monster or a Toyota sludge monster, I am talking about the 95% of the run of the mill engines out there. That being the case, what is the point in changing what has worked very well?

[ October 21, 2004, 05:18 PM: Message edited by: Ugly3 ]

 

[SteveD2]

quote:

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Originally posted by Ugly3:
That being the case, what is the point in changing what has worked very well?

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No reason to change it, but no reason to not change it either. Any other oil will work just as well as the Castrol, and if he wants to use that, that's great too. There's no reason to continue running castrol at all, unless of course he likes that oil.

 

[Chris B.]

So if I did Auto RX and then Mobil 1 or GC would my engine start to leak oil? I've been on here for a while and should know this by now but I never payed much attention to that part of the forum disscution.

 

[Ugly3]

Chris B. -

My approach is very simple. Identify the problem, research solutions, develop plan to fix the problem.

In your case I don't see the problem you are trying to fix. Engine runs well, it is not sludged up, and has been reliable.

Consider a compression test to determine the condition of the ring pack.

If all you are concerned about is switching to synthetic motor oils rest assured that many have switched high milage engines to synthetics with no problems. The seal leaking problems with synthetics were 20 to 25 years ago and have been "fixed" for many years now.

 

[Chris B.]

How much is a compression test? What is good and bad in this test. If it comes out bad what is the fix?

 

[SteveD2]

quote:

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Originally posted by Chris B.:
So if I did Auto RX and then Mobil 1 or GC would my engine start to leak oil? I've been on here for a while and should know this by now but I never payed much attention to that part of the forum disscution.

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You'd probably be ok, but yes, there is a chance it could start leaking.

 

[OffOrWFO]

I bought a 96 suburban with 96k on it. Almost Identical situation. Had no leaks and ran great.I ran an ARX treatment and the mileage went up from 16.5 to 17.5. The was on the exact same 600 miles driven every week so it is a pretty accurate comparison. After the treatment I put in some Amsoil 5w30. I have (or had-haven't looked in a while) a little leak from the belhousing. You know the kind that doesn't hit the ground it's just kind of wet. The leak could be from the intake or a head also. It could also be gone, I'll look tomorrow. The leak could have been there before also and I just didn't see it.

I would do and ARX treatment (mine payed for its self) but the syn I guess is your call.

Also look out for intake gasket leaks. Every one that I know with one of these 5.7s has had the intake resealed before 100k. I did mine when I got it. Some leak internal and not external so get a used oil analysis and check. I also flushed the rad system and put green antifreeze in it. The dexcool kept leaving baby crap looking stuff inside the fill neck, even after a flush an fill. I would never go back to dexcool again.

 

[Slick 55]

GC would be a good choice for that engine.

 

[XS650]

Chris, there should be no problem switching to amodern synthetic at 100k miles.

There isn't much point to going synthetic unless you are going to go extended OCIs. They make sense if you do that.

Do some used oil analysis to determine how long you should run your oil. 6k miles would be a good starting OCI on synthetic interval unless your driving is really rough on it.

On my GM product with 100k miles, ARx did help. If it doesn't run perfectly or the compression is down a bit or uneven, consider running a couple cycles of ARx on good conventional oil before you switch to synthetic. If there is no problem, my experiance on two other cars has been that ARx doesn't fix it

 

[Chris B.]

Ok looks like Auto RX is in this engines future! Thank you for the info everyone and after the arx I'll see how it goes and decided on syn then. Thank you again!