Even new oil should be filtered

[megaboz]

New oil is filtered when you fire the engine which should be sufficient. All oil in the engine travels thru the oil filter before it reaches any engine parts.

I'll have to call you on that one. The fact that you pour into the top of the engine, you already contaminated the engine.

Also I believe that only a portion of the oil is actually filtered at a time. And if the flow isn't fast enough some oil bypasses the filter and goes straight through to the engine.

Also some additives in certain oils don't completely dissolve buy rather are suspended. Like moly, some racing oils, like Joe Gibbs, use a moly that is suspended in the oil.

[Z71]

Also I believe that only a portion of the oil is actually filtered at a time.

Wrong. That may be true for bypass oil filter.
See diagram, this is how the oil system works, all modern engines are built this way.

The fact that you pour into the top of the engine, you already contaminated the engine.

If you are putting in fresh oil your chances on contaminating anything is nil.

All oil filters incorporate a bypass valve. Its to protect the engine. If it did not exist and the filter was plugged the engine would be staved for oil and blow up. Actually many engines (all GM) incorporate a oil bypass into the block/filter base to save the engine in event of a filter blockage. It would be foolish to not have one, 100's of thousands of engine would self-destruct if not there.

[sixdogs]

Could those "contaminated" pieces actually be the additive pack that maybe needs a little heat to blend in? Maybe they were suspended but clumped up for some reason? It doesn't seem possible that contaminates could pass through modern filtering and packaging lines.

[megaboz]

Z71, do you realize that you just contradicted everything you said? If the oil doesn't pass through fast enough it by passes the filter. If it is clogged or partially clogged it is going to bypass. Which matches my original statement.

The engine contamination was based on getting a bottle of something bad like the op was saying he found in the bottom of the bucket. You stated all oil hits the filter first without touching the engine, not possible.

[seacap04]

1 This was not "cheap" oil.
2 This sludge felt gritty. If that is an undissolved additive I would hate to heat it up to redissolve the additive so that it would undissolve again when system is idle.
3 In small hydraulic systems the oil is pumped through the entire system and then filtered before going back to tank. In an engine it goes through the oil pump first.
4 Not all hydraulic filters have a bypass valve.
5 There are a lot of engines out there that still have the oil filler cap in the valve cover.
6 My tractor HST filter is rugged. So I am sure it is a pressure filter. But the oil has to go through the pump first.

[seacap04]

Oh and 7 I don't know about the rest of you,but I have had my tractor at angles that the crank had to be splashing oil all over the crankcase including the lower end of the cylinders.

[Mace Canute]

If you are putting in fresh oil your chances on contaminating anything is nil.

Not correct. The possibility of contaminating your oil is greatest when you are adding oil. Think about it.

[Scooby074]

For future knowledge, what brand oil was that?

[PineRidge]

For future knowledge, what brand oil was that?

I'm curious as well. put that one on my do not buy list.

[MHarryE]

It surprises me seeing people shop for bargain filters because new oil is dirty and the filter on the machine cleans it up. I monitor large fleets and can tell by oil sample results when oil is changed. The samples show higher particle counts immediately after changing and they quickly drop into line in a short time due to the filter(s). Particle size is very important. Extremely fine particles are smaller than the oil film thickness and therefore don't hurt. I think most OEM's have tight cleanliness specs on their oils that is packaged by service centers and labeled with the company name. It adds significant cost but to the user, it pays over the long haul. But we go to 4,000 hours to the first hydraulic oil change, 500 hours for engine, so maybe it's just that we do a better job of cleaning up the parts before assembling, use better, larger filters, and have owners who really follow maintenance schedules.