Valve seals

[Oldnissan]

Hello Everyone,
First I want to thank everyone right off the bat. With that said, I have looked for a fix or instructions on how to replace my valve seals in my 2007 Nissan Titan.
I get a lot of different answers so here's my problem. When I start my truck after few hours a buff of smoke comes out then it quits. I would like to here from anyone who has done this or has taken it somewhere to be done and did it work. Or fix it. Please help.

[scr38]

Before you attempt to replace the seals you should remove the valve covers and check for sludge buildup. If the oil isn't changed often enough, or if a low quality oil is used sludge will build up, causing poor drainage back into the pan, flooding the valve seals with oil. This will cause the smoke.
Clean the valve covers and the PVC valves (or replace them). This may solve the problem.

[Oldnissan]

Thank you scr38 will try this first.