Oil Usage Problem- 94 Isuzu Trooper

I have a 94 Isuzu Trooper. It started using oil at 60,000 miles. Oil is changed regularly but it is always down with another 1000 miles to go before the next change is due. Last oil change - I was down 2 quarts after only 1600 miles of driving. There is no visible oil leakage and no blue smoke. Anyone have any suggestions as to what the problem is?.
I'm new to this forum - perhaps this has been discussed before. Over the years, the dealer has consistently said the high oil usage is normal for this vehicle. It is now @ 140,000 miles.

Some common things to clean/replace is the EGR, and PCV.

Also, you may have sticky rings. Sea Foam oil additive will help (run for 20 minutes drain the hot oil immediatly).

See the faq link below (it is for +98 but there should be some helpfull hints)

Thanks Amigo for your reply. I appreciate the info.
One more question - is synthetic oil recommeneded at all for this suv?.
I currently use a high mileage oil product.

stick with the high mileage stuff.

the sys. may find ways to leak out of your block.

I've been wanting to try that Seaform stuff out.

You can use it in your engine but can you use it in your fuel tank as well?