Motor Guard TP change question

[96 Cherokee]

I just installed a Motor Guard on the engine oil on my "new" 96 Cherokee with 38,000 miles on the odometer. I did an oil change and full flow filter (Eao-15)change at the same time. So I have almost 8 quarts of new Amsoil ACD full synthetic in the engine. Let's say I'm doing 2500 mile TP change intervals. If I do the first TP change at 2500 miles, then I'm throwing away a quart of nearly new oil with only 2500 miles on it. Why not wait until it has 5000 miles on it to start the perpetual OCI process? Thoughts?

Oh yea, I now have 3 bypass filters on this vehicle. Does that make a bypass geek?

 

[deeter16317]

As long as it gets warm, its should be still working...that's how I understand it.

 

[Gary Allan]

I would have recommended a BP80a with a EaBp90 ..but since you've got a MG ..

I'd do the hand warmer test at 3k and add 500 miles at a clip until you find a cool filter. Then you go back to the last mileage mark.

If you do enough clean mileage, you might go 5k on a roll.

 

[96 Cherokee]

Actually in this application, I can see if the flow through the TP is slowing down by opening my oil cap while the engine is running and watching the return flow back into the valve cover. I think I put about 65,000 miles using the perpetual OCI on my first 96 Cherokee before I retired it because the body and suspension were both totally worn out. (engine and transmission still run good) I started out changing TP at 2000 mile intervals, then after used oil analysis were good, I upped it to 2500 miles. Never had a cool MG housing. Even if the TP does not plug up, the additives have to be replenished.

Gary, why do you recommend the EaBp90 over the MG system? On my last 96 Cherokee, I installed my Amsoil dual remote bypass and ran it for several thousand miles. I was not happy with the used oil analysis results, so I replaced it with a MG. used oil analysis results with the MG were much better, IMO. I accept the EaBp90 may be better for someone who does not want to mess with changing TP, but I prefer the finer filtration and cheaper filter changes, along with the better UAO results.

 

[Gary Allan]

Quote:
I think I put about 65,000 miles using the perpetual OCI on my first 96 Cherokee before I retired it because the body and suspension were both totally worn out. (engine and transmission still run good) I started out changing TP at 2000 mile intervals, then after used oil analysis were good,


Just out of curiosity, did you do any used oil analysis after the 30k mark? That's about when the sump is mature. It takes that long for the original sump to be at a lower % than the make up quart. I'll do a brief extension here

I'll assume 6+1 sump size for a jeep (assumed 4.0)

100% new and I'll use 3000 miles

3000 miles 86% original fluid 14% new
6000 73% original 12% 3000 mile old fluid and 14% new
9k 62% original 10% 3k/ 12% 6k/ 14% new
12k etc..etc.

It takes until about 30k+ to have the original sump reduced to below THAT mileage's make up quart. When THAT make up quart travels through the system, then all of them will be in descending order.

I hope I presented that clearly enough.

You were doing 2000 and 2500 mile evolutions, so the mature sump would be lower in miles. It breaks down to so many roll changes, the mileage isn't really a factor in when the sump is as old as it's going to be in terms of product being "processed".

Quote:
Gary, why do you recommend the EaBp90 over the MG system?


Much lower capital outlay and longer service intervals between filter changes. The BP80A w/EaBp90 can be had for about $60-$65 delivered. If the mileage is high enough (less warm up states) you could be looking at lower costs just due to not needing make up oil. You should be able to make 1 year just fine in terms of oil life without a bypass filter.

Quote:
On my last 96 Cherokee, I installed my Amsoil dual remote bypass and ran it for several thousand miles. I was not happy with the used oil analysis results


What are you calling a few thousand miles ..and if I may ask, what did you find deficient that you do not from the MG? Try and keep in mind my dilution factor that I mentioned above. Your "leveling off" period is quite protracted with the MG. You're not in true "free fall" for a very long time. Admittedly, it would mean less at a certain point, but that point is still way out there.

That's not to say that the I consider the practice flawed. It's just often misunderstood and heavily favors cheaper fluids where time would be as much, if not more of a factor.

 

[AlaskaMike]

For the TP filters I only see 2500 mile change intervals recommended in diesel applications. In those applications the filter is absorbing quite a bit of soot which you don't have in a gas-powered application.

I'd bet you could go much farther than 2500 between changes, but Gary's recommendation for determining just how far seems like a good way to go.

 

[Gary Allan]

Yeah, gas and diesel load filters differently. Oil fatigue differently too. Soot production is a basic component of the combustion process w/diesels, while the byproduct production in gas is more related to the fuel enrichment process. With soot under control, a diesel can get longer miles out of a lube. Regardless of filtration, gas is going to fatigue the oil. A TDI with a bypass can do 25k and still be suitable for continued use. Most oils in most engines would have a hard time with that even if it was a dry sump with only fine filters as the oil tank(s).