to change oil or not????

[landrovered]

"Rust inside an assembled engine or transmission can occur any time the oil is allowed to drain off a component due to infrequent use. Engines which are operated daily or weekly seldom encounter this problem, but many street rods, muscle cars, and race cars are often stored for several months without being turned over or fired up. This is a recipe for rusting problems.

Water and low temperatures significantly increase the propensity to rust. Engines fired up infrequently generate a tremendous amount of condensation. If the engine isn’t allowed to completely warm up, this condensation remains inside the engine. (Water will not burn off until the internal engine temperature (oil temperature) reaches 212 degrees F.) This water will then attack any surface which isn’t adequately protected by either an oil film or a vapor phase rust inhibitor ( new tools which often contain a packet of vapor phase rust inhibitor to prevent rusting in shipping and storage)."

Driven Racing Oil Website.

It would appear we have a consensus on water and fuel in the oil as being the problem. As I stated correctly, running the engine periodically to temperature is key in preventing rust.