Originally Posted by HondaRules!

Particle sizes is what he's referencing. Most synthetics use smaller particles. This causes them to effectively not stick to everything, and the agents help it to do just that. It forms more effective boundary layers and such.

However, Mobil 1 is an exception. It was called "tri-synthetic" because it consisted of 3 different sized particles. It was also one of the only synthetics you could run effectively in a used engine for a long time, due to the increased wear and gap caused by regular oils.

IF you changed from regular to synthetic (at the same viscosity), and saw a 15 psi drop in oil pressure, all I can say is that regular oil was caked on pretty heavy, forcing it to have to put out a lot more pressure to create the same oil delivery. Kinda like your arteries on a diet of high cholesterol for a few years.

Synthetic base stocks are actually more true to the viscosity, and they react better to the expanders, giving them increased thermal breakdown, and wear intervals. They should actually show better pressure, as a general rule, especially once hot!