Synthetic can be thicker or thinner?? It depends on its viscosity. Its got two SAE numbers eg 20W/50. The higher the number the thicker. The number with the W is the winter/cold temp, and the other is hot (-20 and 99 degrees) In cold, you want it to be thin, so its not too thick to turn over etc, and thicker as its warm so theres no metal to metal contact. I think that the thickness only depends on the SAE number, not whether its synthetic or not. Does that answer your question, or did you already know that??!!
Incidentally, if your at all interested SAE stands for Society of Automotive Engineers.
I suppose i could add that throughout the cars life its had its oil changed every 7000 miles, and has no problems. Also if you want to stop the tappets then use the oil that "sticks" then it coats everything instead of draining into the sump.
