6.2 Blow bye

[Gerry]

Hello im new to this forum
I have a 1986 chevy k5 blazer 6.2 diesel with 380 000 miles not km engine still original
I have it since 1989. Now getting blow bye from both oil filler and dip stick. New cdr 2 months ago. It starts good and no loss of power but im going through lots of oil. No leaks and very to no exshaut or “ smoke” at tail pipe. Aside from complete engine overhaul any suggestions for additives?? Always used 15/40 faithful on oil changed. Now thinking of changing to sae 30 grade thicker.
Looking for that wild card
Thank you

[Robyn]

Welcome to TDP....

Very nice to see a 6.2 with this many miles on it.

Sadly when things reach this many miles there is little that can be done in the way of "Magic" to stop the symptoms you are seeing.

The Blow by is caused by combustion gases leaking past the piston rings.
It is not all uncommon to see the rings get stuck in the grooves after this many miles.

Additives can be a good thing, but they will not heal up a worn engine.

I have two suggestions .... Continue running the rig as is, or plan to yank it out and make repairs.

A low cost repair can be done by removing the pistons and lightly honing the cylinder bores with a "Bottle brush" hone to remove the glaze on the cylinder walls and replacing the rings.

New bearings can be installed too.

If $$$$$ are a big issue the heads could be left alone....just clean them really well and make sure the surface that bolts to the block is spotless (Remove all old gasket material...same with the deck of the block)

Replace the rear main seal
Replace the timing chain and cover seal

New gaskets
NEW HEAD BOLTS (Follow tightening instructions that come with the bolts)

A quicky overhaul

This will get the old girl back up and running and likely give you many more miles

Good luck

Just a thought

TRY ADDING A CAN OF STP for high mile engines.
It might help a bit

[DmaxMaverick]

You might try running some MMO (Marvel Mystery Oil) or ATF for 500-1000 miles. They can help with hardened seals and loosen sooted/stuck rings. MMO is a little better/faster, in my experience. Do this before trying to fix the oil. Also, changing oil brands and/or types can help significantly with oil control. Using SAE 30, or 40 (recommended, if you do that) won't be a good choice for northern winters. Full/true synthetic mulit-viscosity is a better option, even if 5w-40.

[Gerry]

Thank you for both all suggestions