Cat has issued several bulletins saying not to prefill. The consequences from pouring some contaminates on the clean side of the filter can be worse than a hundred dry starts.
And there are containments, a few years ago I had a brand new unopened gallon jug of Delo with a dead mouse in it. Wouldn't have even spotted it except it got caught in the funnel.

 

Huh, never heard of DeloMouse oil before.

 

YUP, You've got to prefill
why wouldn't you?????

 

pre fill it's the only way!

 

Ed Shovelhead knows I fill the cars upside down on a regular basis but those VW's with the wide center of gravity are tough to flip over.

 

So if we don't pre-fill... think it would be a good idea to disable the fuel (on a 12v, unplug the pull-up relay) and crank until you get oil-pressure, so at least you're only at crank speed instead of run speed without oil? or am I just way too ****...

 

I figure it this way:

It is true that you could potentially get dirt in the filter while prefilling it, BUT you are more likely to get dirt in the filter as you are getting it in place and spinning it on if you are not carefull.

SO, the fact that it is filled or not filled SHOULD not have a bearing on cleanliness.

Why not fill the filter, and be carefull replacing it, just as you would be if you were installing it empty?

JMO

 

Pre filling the filter is a nice idea but the devil is in the details. The biggest problem is introducing contaninants such as dirt or foil or other things. The bearings must have clean oil. Pressure is optional, clean is not. If it makes someone feel better, and they are sure they are not introducing any dirt, then pre-filling is fine. I think as a general practice it's not a good idea.
The whole argument for pre-filling is based on the idea of what has been called a "dry start". Actually, the bearings are not "dry" on startup even after sitting for a long time. And damage caused by metal to metal contact in the bearings is not prevented by oil pressure. It is prevented by the oil "wedge." A situation that happens in a turning or sliding bearing with oil present. Many pieces like rocker arms or push rods could be oiled about once a week and be fine. Upper rod bearings never get pressure. And a little splash on the timing gears once in a while should keep them happy. It's only the rods and mains that need oil pressure fairly consistantly to keep them cool and flushed out so the oil wedge can work, and contaminants will be pushed out. Also the cylinders need splash and that doesn't start till the pressure is up, but running slow for a few seconds is not going to score the cylinders.
I know these are modern highly stressed engines but startup is not that stressful and remember, older cars only had a splash system with a dipper that dipped into the pan too throw oil around. That's all they had. Older farm engines had open crankcases with a grease cup on the rod and mains. A quarter turn about once a week was all you needed. It's the presence of oil not the pressure, at least at slow speeds and cool running, that keeps the engine alive.

Wetspirit

 

Interesting and informative read Wets...and I agree with the contamination point, but if filling the filter gets rid of 5 seconds of air I'm prefilling. Thanks for the post.

 

Another note on "DeloMouse", where ever there are mice there are mouse turds, great size for plugging a cylinder nozzle and easy to miss.
Doubt that any oil makers also manufacture their own jugs, I'm sure they are shipped and stored for who knows how long without a lid. Plenty of time and opportunity for contaminates to enter.
I'll take my chances with "dry" starts.

Best of both worlds would be to only pour the pre-fill oil into the dirty side of the filter.
Center hole I believe???

 

No the center hole is the clean side. When I fill mine (it takes a long time) I try to pour slowly in the out side holes.

BTW I have a brother named Tom.

 

This is exactly what I do as well. I slowly pour a quart of oil into the outside ring of holes being careful not to let it overflow into the center hole. It only takes a few minutes and I usually do this when I'm sitting around with nothing to do waiting while the oil is draining from the pan.

Best of both worlds.... freshly filtered clean oil and no "dry start".

 

Never tried it on an CTD oil filter but on the spin on type fuel filters a 1/2'' pipe nipple will block the center hole and also give you a place to hold on. I bet a pipe nipple, maybe 3/4'', will fit right in the oil filter center.

 

I can really understand how much we enjoy our CTD's.
150 cast ballots and less than 8% don't pre-fill there oil filters.
I'm not saying right or wrong are flaming any side. Each side has it's opinions. Just the vast majority do the little extra to maintain something they care about.
But, on the other hand ....... the other 8% believe that they're protecting their investment by not pre-filling.
It's been a good post with alot of good views both ways.

 

i always prefill every oil filter in every engine that i service no matter what. if it is sideways, or upside down, i just put in what i can. I also always wipe the bottom of the filter head with a clean rag and use a new plug gasket every time.