Looking for thoughts on installed tranny filter (OEM) life expectancy in the "severe" environment while accumulating 8000 miles per year.

My wife is the main driver of our 1980 450SEL. She accumulates mileage at a rate of about 8000 per year, most of it local short haul. This puts it in the "severe duty" category.

Under "normal" operating conditions, the fluid AND filter get changed every 30k miles. Add "Severe" and there is an additional fluid ONLY change at the 15k miles mark.

I have over the years always changed both. My reasoning was that due to the low mileage accumulation rate over time, I wanted to keep a fresh filter in there (e.g. less that 3 years old).

"Normal" mileage accumulation is at 12-15k per year. In theory the filter gets changed every 2-3 years. In my case it won't get change but every 4-5 years if I use the 15k fluid only procedure.

It all really comes down to, how long can an installed tranny filter (OEM) maintains it's integrity and efficiency in the "severe" and low mileage accumulation environment?

I'll probably keep changing it 'cause:
- It's not that hard to do
- I get a chance to inspect what has collected in the bottom of the pan
- Mainly peace of mind (probably the most correct reason)

Thoughts anyone on filter life expectancy?

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S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)