Z 5718 questions

[Jim]

Hi I have a Zetor 5718 -73. When I drive it longer distances, say over 2 km it gives a "blury" noice and a lot of smoke comes out of the exhaust pipe. If I then give more gas a couple of times it puffes and then it's OK again for about maybee 5-10 minutes. Then it all repeats itselft again. What could be the problem?
Also I'm thinking about changing all the oils. I have used 15/40 W for the engine oil. Can I use that for gear/hydraulics aswell?
/Jim.