My wife has a 2007 Toyota Sienna with 3.5 v-6. I put in a magnetic oil pan drain plug at the first change, and changed oil 3 times with Toy filter and Pennzoil YellowB 5w-30 every 4000 mi. Almost nothing on the magnet each time I changed oil.
Then I used a free oil change coupon at the dealer. When I changed oil after 4000 miles on the dealers oil, the magnet had a whole bunch of the "silver black goo" on it. I changed that oil with the same Pennz YB 5w-30 I had been using. The other day I changed oil again with Pennz YB, and the magnet had almost nothing on it again.
So I don't think I'll use any more free oil change coupons at the dealer.
Then I used a free oil change coupon at the dealer. When I changed oil after 4000 miles on the dealers oil, the magnet had a whole bunch of the "silver black goo" on it. I changed that oil with the same Pennz YB 5w-30 I had been using. The other day I changed oil again with Pennz YB, and the magnet had almost nothing on it again.
So I don't think I'll use any more free oil change coupons at the dealer.