[RocktimusPryme]

Originally Posted by Aluminum Chief

I run diesel oil with a bottle of Comp Cams Break in additive every oil change.

Would that not be overkill? If you use a diesel oil that in theory already has sufficient additive for a flat tappet, and then add the external additive wouldn't that result in too much zinc?

When I was looking into this I seem to remember reading that an overabundance of zinc anti wear additive can backfire and actually create wear.

[Sirrotica]

Originally Posted by RocktimusPryme

Would that not be overkill? If you use a diesel oil that in theory already has sufficient additive for a flat tappet, and then add the external additive wouldn't that result in too much zinc?

When I was looking into this I seem to remember reading that an overabundance of zinc anti wear additive can backfire and actually create wear.

You're correct, too much zinc is as bad as too little when it comes to oils. As in many oil additives they screw up the OEM designed additive package by being heavy on one or two of the ingredients, throwing the engineering of the total package off.

Petrochemical engineers urge people to use the correct oil for the job at hand, rather than trying to re-engineer their own blends with additives.

As far as spending a ton of money on oil and using the same oil filter that is inferior you're really wasting money. Oil does not lose it's ability to lubricate, it gets dirty rather quickly and then starts abrading internal engine parts with the microscopic solids that full flow filters physically cannot remove.

Typically the best full flow filter will only filter down to 20-40 microns at an efficient level. By pass oil filters typically filter down to the 1-5 micron range at 98 % efficiency. Makes the engine as well as the oil and additive package last many times longer than standard filters.

Everything I own is high mileage, the lowest mileage vehicle I own is 105,000 miles on it. My wife's car has 300,000 miles on it that was bought new in 2008.

Pennzoil synthetic 10W-30 in the gas vehicles, Shell Rotella 15W-40, or Shell Rotella full synthetic 5W-40, in the diesels. I use by pass oil filters on the 140,000 mile LS2 GTO, and the 270,000 mile 6.5 TD. The vehicles I haven't yet converted to by pass filters get the Purolator Boss synthetic media filters.

The quality of the oil filter is more important than what brand of oil you purchase. The high quality oil filter also allows oil changes to be safely extended. The by pass filters allow me to extend drain intervals 3-4 times that of a conventional filter, usually 30-40,000 miles between oil changes.

I believe the high mileage vehicles I own prove the oil filter has more to do with low maintenance of engines rather than which brand of oil you use. I however buy the best value oil, (Pennzoil synthetic, Shell Rotella) without spending an arm and a leg for it, then make a concerted effort to keep the oil clean. I intend to have the whole fleet equipped with by pass oil filters during this year.

1988 IH S1600 7.3 IDI Diesel 208,000 miles
1993 K3500 6.5 Turbo Diesel 270,000 miles, (By pass oil filter)
1995 C3500HD 6.5 Turbo Diesel 246,000 miles
1999 Grand Prix 3.1 105,000 miles
2005 GTO LS2 140,000 miles, (By pass oil filter)
2008 Vibe 1.8 299,000 miles

[ScumOne]

I agree on the oil filter quality being important. I usually search out for the deep filters and avoid the shallow ones. In the 69 Bird/400 w/ac I'm using the Wix 51049 filter.

[455Grandville]

Originally Posted by Sirrotica

1988 IH S1600 7.3 IDI Diesel 208,000 miles
1993 K3500 6.5 Turbo Diesel 270,000 miles, (By pass oil filter)
1995 C3500HD 6.5 Turbo Diesel 246,000 miles
1999 Grand Prix 3.1 105,000 miles
2005 GTO LS2 140,000 miles, (By pass oil filter)
2008 Vibe 1.8 299,000 miles

If those 6.5 Turbos have never been apart you’re doing much better than most I’ve seen which tend to go bad at 150-200,000 miles.

[Sirrotica]

Originally Posted by 455Grandville

If those 6.5 Turbos have never been apart you’re doing much better than most I’ve seen which tend to go bad at 150-200,000 miles.

There are lots of people that have no clue what it takes to keep 6.5 diesels together. Not to say that GM didn't have bad castings in the earlier ones, cracked blocks right up through the bulkheads just like Pontiac does when you overstress the blocks. The harmonic balancers have a habit of coming apart, and if you don't catch them they break the crankshafts soon after the balancer goes south.

They also had a propensity to crack cylinder heads from overheating, and blow headgaskets. ARP studs and good headgaskets usually solve that problem, but mine still have the factory bolts in the heads, one in the 95 is bubbling in the radiator so it probably has either a cracked head or a headgasket starting to go, I just acquired that one within the last 30 days, we'll see what happens with it.

The 93 runs just fine, has only had a waterpump changed out since I bought it in 2011, and I had to change out the injection pump when it took a dump.

They can be bought pretty cheap, and because they are mostly not heavy on electronics, you can fix them cheaply. Same engine that the military Hummers used until AM General quit making them.........

I guess I lucked out with my two so far...........LOL

[455Grandville]

Originally Posted by Sirrotica

There are lots of people that have no clue what it takes to keep 6.5 diesels together. Not to say that GM didn't have bad castings in the earlier ones, cracked blocks right up through the bulkheads just like Pontiac does when you overstress the blocks. The harmonic balancers have a habit of coming apart, and if you don't catch them they break the crankshafts soon after the balancer goes south.

They also had a propensity to crack cylinder heads from overheating, and blow headgaskets. ARP studs and good headgaskets usually solve that problem, but mine still have the factory bolts in the heads, one in the 95 is bubbling in the radiator so it probably has either a cracked head or a headgasket starting to go, I just acquired that one within the last 30 days, we'll see what happens with it.

The 93 runs just fine, has only had a waterpump changed out since I bought it in 2011, and I had to change out the injection pump when it took a dump.

They can be bought pretty cheap, and because they are mostly not heavy on electronics, you can fix them cheaply. Same engine that the military Hummers used until AM General quit making them.........

I guess I lucked out with my two so far...........LOL

Plus they used cast cranks (in a diesel !) which was a weak spot as well. They also tended to run hot but GM fixed that around 1995 with dual thermostats. There was a control module under the intake that liked to go bad and the solution was to relocate it. Imo if you leave them stock except for updates and don’t overwork them they’ll do ok.

I just preferred the International 6.9 and 7.3s that Ford used a lot more as they were pretty tough engines. You just can’t expect them of the 6.5s to compete with these new diesels but they are much more simple and cheaper to repair.