hello, I recently took the job as a maintenance supervisor for a nursing home. the home has an outdoor generator, a generac 17kw.. I was checking the lcd displays history, and I seen that it had several "low oil pressure fault codes" I seen that it was setup to exercise itself once a week for 12 minutes, and has been failing with a "low oil pressure" fault I pulled the dipstick and seen the oil was murky, full of moisture. I checked the intake and air filter housing, both had condensation forming.. I noticed there was no winter kit on the genset, the winter temps range from -20 to -35 so I installed a winter kit on the genset, so now the battery, oil filter and intake all have warmers on them. I figured the condensation must of been caused from it starting cold then warming up during the exercising then cooling down and causing condensation. I drained the oil and chased it with good oil until the oil was clear.. and changed the the oil filter.. the genset started 1st try and ran good with no problems, i let it rest and did another start and it worked fine. my question is, when i was draining the murky oil from the bucket into the disposal barrel, i noticed what looked like bits of rock in the murky oil. the bucket was spotless before I drained the oil. i pulled the air filter again and looked and it was fine no debris. I can not see how anything could be in the engine, since it would have to get by the air filter. almost seems impossible. I have a picture of the debris.. just makes no sense how this could of got into the oil.. any help would be appreciated.