195 issues

[Samson nich]

my 195 can't start until I add engine oil and petrol through the air filter.
so I need you guys help

[mike90045]

Both of those items will help cure low compression. 
Oil seals the rings better, petrol lights off easier.    Will either one work, or do you need both together ?

Valves could be bad too, not seating well.  any more info about the engine history ?

[glort]

How old is the engine? If it's not done a lot of work the problem is probably something simple. If it's older, the possibilities become wider.

Best to methodically work through the thing starting with the basics to make sure they are all in spec. Start with valve clearances, fuel Filter, injector spray check, compression etc.
I have used a lot of alcohol to start diesels but if you need oil as well then I'd say something is either worn or well out of wack.  Could be something simple like tight valves or the thing may need a rebuild.

By working through and making sure the basics are right you'll get to the answer sooner and not spend money on the wrong soloutions.

[38ac]

As they said more information would allow for more accurate answers instead of guesses. 
Just these would help a lot.
Does the engine have a lot of hours?
Does it run right after it does start?
Has it ever started easily?
Has it sat for a long period of time unused before this started?
What are you using for fuel?
Does the injector "creek" when cranking?

Adding oil raises compression but it also masks fuel injection problems