Smoke from exhaust when pulling away from stop

[Manu]

I have a '93 camry 4cyl.
When i start it for the first time in the day it goes out fine ( although initially it gives out a little white smoke). After driving it for quite a distance (8-10 miles) and letting it rest, when i start driving the car again, it leaves a huge puff of white smoke behind.
Then the car works normally until brought to a stop. This usually happens when the car is kept resting for a short duration ( less than an hour or so).

Requesting your suggestions.
Thanks

[InTeReX]

check your oil lately?
change your oil lately?!

Not sure, just some guess...good luck

[Manu]

I am changing oil at every 3000miles (as suggested in some of the discussions) but the problem is still occuring.

[5Sfte]

Do you have aftermarket muffler and piping, or stock exhaust?

[Hamsterman]

my girlfriend's 3000GT does this and it is a pain, it was one of those things that we started puttin 25W50 oil in to try and keep from burnign soo much with the heavier oil, and then took it in to get it looked at. She has seal damage and a bunch of crap that woudl be probably over a thousand $$$ to fix to we are just dealing with burning oil- in her case there is a "problem" but for now and a while it doesn't need to be fixed- have you taken your car to a mechanic?

[BLUEMEANIE]

Gen3's are known for leaky valve seals.

[Tercel GTS]

Sounds like coolant seepage to me, white. I'm thinking once you have the water up to temp it's making the way while under pressure into the cylinders, once the pressure drops it stops, and the resident heat built up in the metal evapoates most out overnight.
Is the oil milky or overfull?
Go get a pressure check on the cooling system run while engine is warm, have them remove the spark plugs before applying the pressure. Listen for a hiss in the spark plug holes. Also spin the engine over while the plugs are out for at least 1 revolution, have someone watching for water to come out the holes.
Last thing, take the radiator cap off(while cool), crank the engine and allow it to warm up, watch for bubbling or water to spew from radiator.
Any of these symptoms can be a bad head gasket, warped head, or a crack in the head or block.

[Manu]

I have got that checked by the mechanic and he detected none of any such issues (coolant leakage).

The oil is in perfect colour.

The smoke comes out only while accelerating for the first time after making a small stop ( ranging from 5 minutes to 60 minutes).

Also when the smoke comes, i can hear a knocking sound. The mechanic was also saying that this is due to the leaking valve seals. But the huge puff of smoke gives me shivers.

Will the use of dense oil not cause any problems to the engine ( long term/short term)?

Thanks!