Matt16

I am a stickler for changing my oil every 9 months (Mobile 1 synthetic). I had a bit of a knocking sound coming from the bottom end and when I did my filter changed that eliminated the noise completely. Interesting. Guess 22REs like really clean oil.

My99

SO how many miles did you drive during that 9 months?

iamsuperbleeder

Seriously, I'd let my truck set for 9 months, and if I only drove it 1500 miles, then I wouldn't change the oil; I'd go the next 1500 miles. The point is, I think the "month" rule of thumb is just so you don't forget to change it. The average person puts about 3000 miles on a vehicle in 3 months (roughly an average of 30 miles a day), hince the phrase "every 3 months or 3000 miles". With conventional oil, I usually go about 4 1/2 months, only because that's how long it takes me to put about 3000 miles on her. I wouldn't rely on the months thing, I'd keep track of your mileage. For nine months, their probably saying "9 months or 9000 miles". If you went quite a bit over 9000 miles (which I think is crazy IMO, I'de never put that many miles between oil changes, I don't what kind of oil it is), then I would say that you either A) broke the oil down so much that it just didn't have its viscocity like it needs to, or B) after that much time, the oil filter probably just got clogged from normal ware and tear, possibly even a little sludg build up in the filter.

4Mogger

You have correlation but I do not think that translates to causation.

1500 miles on Mobil1 in 9 months would not cause knocking where fresh oil would eliminate the same symptom IMO.

mt_goat

I wonder if the filter failed somehow, did you cut it open and have a look at the inside?

Matt16

Drove for the weekend, noise is back, just quieter than before. I noticed my oil pressure is lower now as well.

I drive the truck a couple times a week. Mostly errands and highway trips with some offroading. Its not a very practical city car. I did about 3000kms, which is about 1900 miles in 5 months.

iamsuperbleeder

the noise it back already?

how did the oil look last time you drained it out? did it seem abnormally thin, or normal.

if it seemed fine, I do as suggested and try to dig into the filter that was originally on there, and the one your running now, to see if there's large amounts of fragments building up in it.

if not, the oil pump may be shot.

Matt16

I had my oil pump out in October. It looked fine to me, though I had never seen an oil pump before. It certainly was snug fitting though, no slop. Does this mean its fine?

I know the oil pressure gauge is pretty crude. Is the sender likely the problem. The oil pressure seemed about halfway up the gauge at 2500rpm and I think it stayed there.

MMA_Alex

you check the clearance between the rotor and the sidewall to see if the pump is still good.

you did top the oil up after the filter change right?

Matt16

I didn't check the tolerances on the oil pump. I did top up the oil.

4Mogger

Just remember that synthetic oil runs at lower pressures than the dino stuff. Should be about normal at highway rpms but I notice my trucks always run on the low side with the stock oil pres. gauge.

And it is more pronounced with the less viscous oils. I run Amsoil series 2000 in 0 W 30 in my 4Runner and oil pressure barely reads at idle. But it has been that way for almost 130K miles since I switched to Amsoil. That silky stuff just flows with less resistance and that means less indicated pressure.