Buying a 1995 f25 diesel from a frien and he ran unleaded gas in it and now it blows alot of white smoke

How long has the gas been running through the diesel system. If it was only a short time you should be ok. You definately need to syphon out all of the gas from the tank and the ENTIRE fuel system. The fuel pump in diesel engines are lubricated by the diesel itself so you may have an issue there. Overall i think you should be fine if there wasn't too much driving with the wrong fuel. Just make sure ALL the unleaded gas is out of the system and make sure you prime the fuel system properly when dont or else it will not start if there is any air in the system.

Blown head gasket an the white smoke is the truck burning off the antifreeze thats leaking into oil big job to repair 1500$at a cheaper shop...bad to run without fixing due to antifreeze thins oil and internal damage to engine will result....thanks for using fix ya.good luck friend never ran gas a diesel will not run on gas and will shut down almost imeditely if clean diesel is dirtied in any way...