Engineers why not use Original Filters,Spare parts. what is the bad effects this type of maintenance/service on machineries/heavy equipments ?

Using non genuine filters could result in severe breakdowns, and additional costs to any machine, which leads to downtime.

I may say, the genuine spares consume more capital and lead time is high.

The bad effect will be equipment reliability is lower compared using the genuine spare. The original maker won't give the details of the parts in terms of fits and limits. This is another issue that engineers must consider when using the fake spare parts.