Everyone perceives severe service when they own one of these things. The same engine is expected to do it's job day in and day out and competes with other power plants for cost of maintenance. If you're not tinkering with it or operating it at higher rpm constantly, then I don't see it being severe.
We've got nearly 20k of people here that perceive severe here. I tend to think it's some badge of honor.
The out of phase comment is that you're starting with a new sump that can take you out to 7.5k/15k. So ...12 quarts gives you (up to) 30k of usage before additional oil is bought. TP gives you 24k @2k 36k@ 3k per ...but if you're never changing the sump, the sumps aren't comparable in age.
How do you handle the perceived difference between severe service and normal service with a tp filter? One would assume that if your duty is truly severe ..that the tp roll should need service more often.
Don't get me wrong. I own a vintage Frantz and Motor Guard ..and I also have a superb PALL canister filter that uses DOE (double open end) cotton wound filters. This is in addition to the Amsoil Dual Guard. They all do a great job.
The thing with a tp/pt filter is that it depends on the perpetual sump to make it pay ..if you're operating at some sensible economy.
@ 2k tp changes it takes 60k to reach the mature sump
@ 3k tp changes it takes 90k to reach the mature sump
I'll show you the quick version. Keep in mind that with every quart added due to tp change, that you're also removing a percentage of the last quart you added.
(we'll just use 2k for the moment and we'll assume)
2k and a 12+1 sump)
0k 100% new sump
2k 92.3% original sump
4k 85.2%
6k 78.6%
8k 72.6%
10 66.9%
12 61.8%
14 57,0%
16 52.6%
18 48.6% (here, at 18k about half your sump is 18k old ..and the added oil is NOT new)
20 44.8%
22 41.4%
24 38.3%
26 35.4%
28 32.6%
30 30.1%
32 27.8%
34 25.7%
36 23.7%
38 21.9%
40 20.2%
42 18.3%
44 16.9%
46 15.6%
48 14.4%
50 13.3%
52 12.6%
54 11.3%
56 10.4%
58 9.6%
60 8.9%
62 8.2%
64 7.5% (here is where the new added oil is equal to the oldest oil in the sump).
If you go to 3k per tp roll..then it's 96k