Oil burning question on GM Vortec 350

[Chris B.]

I bought a 1997 GMC Sierra this past March with only 75,000 miles on it and it is like new in and out. I don't drive it much and I'm 2,500 miles into a Auto Rx cleaning cycle using Castrol GTX and a Super Tech oil filter. The level on the dip stick has been dropping over the 2,500 miles and I added 12oz and that brought it almost back to the full line on the dip stick. So I thinking it has burned between 12 to 15 oz in the 2,500 miles. I'll do an oil change at 3,000 miles.
Is this considered a lot of burned oil? I have never had a vehicle that burned oil before.
I'm hoping it will stop after the Auto Rx cycle is done and I get a few thousand more miles on her. The original owner averaged only 1,900 miles a year for the past 10 years so the truck sat a lot. Thanks for any advice or input!!!I'm hoping it will stop after the Auto Rx cycle is done and I get a few thousand more miles on her. The original owner averager only 1,900 miles a year for the past 10 years so the truck sat a lot. Here is a picture of the truck. Thanks for any advice or input!!!

 

[Merkava_4]

Originally Posted By: Chris B.

I'm hoping it will stop after the Auto Rx cycle is done


Did someone tell the rings were sticking?

 

[Chris B.]

Originally Posted By: Merkava_4
Originally Posted By: Chris B.

I'm hoping it will stop after the Auto Rx cycle is done


Did someone tell the rings were sticking?

What?

 

[Merkava_4]

Originally Posted By: Chris B.

What?


Oil consumption. There's some people that believe oil consumption
is caused by stuck piston rings and that Auto Rx is the cure.

 

[Chris B.]

Ok. I had a bottle left over so I figured it couldn't hurt. I had a rear main seal leaking and tried the Auto Rx and the leak did stop 100%. But the next time I tried Auto Rx to clean up some sludge it did nothing. Figured it would not hurt to run a cycle in my truck.

 

[Merkava_4]

Originally Posted By: Chris B.
But the next time I tried Auto Rx to clean up some sludge it did nothing.


That doesn't surprise me.

 

[hounddog]

Its a old style Chevy motor. They use some oil. I sure7 wouldn't lose sleep of the amount you added.

 

[Gene K]

1 Qt per 3000 miles used to be considered normal for the Small Block Chevy. After winter you might try Shell Rotella T5 10W30. It seems to do a good job on keeping rings clean and can be treated basically like a synthetic for drain intervals.

Thats a very clean truck.

 

[Merkava_4]

Originally Posted By: hounddog
Its a old style Chevy motor.


Yes, and they do well on old style oils, but people are always trying to cram CAFE oils down them.

 

[95busa]

Old engines do not always need old style oils. The Vortec engines were specced for 5w30 oil from the get go, as most GM engines have been since the '80s. The LT series for instance must use GM 4718M spec oil. That spec has been around since at least 1992 and is still represents a very durable, robust oil. The Vortec is a well developed sequential EFI engine, and like most SBC are very durable. I would say definately stick with an Xw-30. I think any good oil will do, and agree with the Rotella 10w30.

 

[law3500]

No, that is not excessive oil consumption. GM considers 1qt per 1000 miles acceptable. Many including me do not agree with that spec but 15 oz in 2500 miles is just fine at that age/mileage. Auto-RX may help. Make sure the PCV system is clean.

 

[The motor guy]

Probably the auto rx burning off. Plus it looks like you short trip this thing alot so it will burn more oil versus running it on long trips. Due to the engine being loose when cold.

 

[Bayman]

Originally Posted By: Chris B.
Ok. I had a bottle left over so I figured it couldn't hurt. I had a rear main seal leaking and tried the Auto Rx and the leak did stop 100%. But the next time I tried Auto Rx to clean up some sludge it did nothing. Figured it would not hurt to run a cycle in my truck.


https://bobistheoilguy.com/forums/threads/question-on-auto-rx-is-it-working.98631/

Chris, how is your Volvo doing these days.

 

[Chris142]

1qt in 5000. Miles is very good

 

[tig1]

What burned oil? Your engine is using a qt every 5-6K. That's fine. If you suspect a little sludge, then forget the RX and change to M1 5-30HM.

 

[Chris B.]

Hey Guys,

I had a 1997 2 door Tahoe with the same Vortec 350 with 140,000 when I sold it to help buy this truck. I needed a real bed so the Tahoe had to go. I used Castrol GTX in it for years and got a Blackstone UOA on every oil change. Most wear was extremely low and lots of single digits. In fact Blackstone stated it was the lowest wearing GM 350 they had on file. That is why I'm using Castrol GTX 5w30. Maybe it was not the Castrol and it was just a very well built engine??? The Tahoe engine was burining a tiny bit of oil too just before I sold it I think. It started to drop a little on the dip stick.

Think I should try Castrol GTX for a while and see my UOA results befor trying the Rotella T or something else?

 

[Chris B.]

Originally Posted By: Bayman
Originally Posted By: Chris B.
Ok. I had a bottle left over so I figured it couldn't hurt. I had a rear main seal leaking and tried the Auto Rx and the leak did stop 100%. But the next time I tried Auto Rx to clean up some sludge it did nothing. Figured it would not hurt to run a cycle in my truck.


https://bobistheoilguy.com/forums/threads/question-on-auto-rx-is-it-working.98631/

Chris, how is your Volvo doing these days.


I'll give you an update tonight when I get home!

 

[4x4chevydude]

I have the same motor with 140k and its been burning oil as long as i can remember every 1k I check it and top off as necessary...I have tried all oils including HDEO 15w40 and HM oils but nothing seems to slow or stop it so its a great motor and a great truck I just live with a little oil consumption. Dont worry about it just keep it filled and drive it for a ton of miles to come.

 

[hominid7]

Great find. That's one clean truck.

I agree with the others, 15 oz in 2,500 miles, especially while running an auto RX, and using a different oil and/or viscosity from the PO, is something i'd be happy with. Due to the age, perhaps something like Pennzoil/Castrol/Maxlife HM 5w30 would be appropriate at your next OCI.

The last GM 350 i drove used about a quart every 500 miles

 

[Merkava_4]

Originally Posted By: 95busa
Old engines do not always need old style oils. The Vortec engines were specced for 5w30 oil from the get go, as most GM engines have been since the '80s.


That specific engine does not do well on 5w30. I've seen it happen in the UOA
section time and time again. Being an armchair tribologist, I'd recommend 10W-40.