The oxidation by-products forming in diesel engine lube oil can cause （）

A.increase ignition delay
B.affect fuel oil metering
C.affect engine performance at low speed
D.only disappear due to fuel oil abrasion

A.oil foaming will occur
B.large quantities of oil are consumed
C.lube oil viscosity is always decreased
D.corrosive by-products are usually formed

A.keep the parts immersed in diesel fuel
B.always keep the plunger and barrel together
C.work over a linoleum-type surface
D.all of the above