My truck takes the cannister filter with the clear bowl so you can see the filter. Every truck i've had the canister would fill up slowly and be about 3/4 full by about 20,000 miles. This truck fills up quite quickly it will get about 1/2 full after about 10 miles and I have 4,000 miles on it now and it filled up to the top of the glass. Mechanics say some do that and some dont. any ideas on why this is happening?