Originally Posted By: KGMtech
If you routinely tow a trailer in very hilly mountains, it might be better to use DOT 4, but the DOT 3 should suffice. Little bit more resistance to boiling with the 4. Not much of a difference in price IMHO.
Or very high speed with a lot of hard braking like when you track your car, then DOT-4 is needed. Otherwise, DOT-3 is sufficient for normal everyday driving.
My E430 spec'ed DOT-4 but I replaced with DOT-3 since 2004-2005 and no problem what-so-ever. Main benefit is I need to bleed once every 3-4 years instead of 2 years.