I have a 2003 Honda Accord (V6). I've read in the manual that I need to use Genuine Honda power steering fluid. Is this a must or can I use any power steering fluid. The Honda one has a reddish/pink color to it. Is the chemical make up any different than other power steering fluid? Is this a marketing gimmick from Honda?
You do not need to use "Genuine Honda" power steering fluid. You do, however, need to use power steering fluid made for Hondas/Acuras. If you look at any manufacturer specific manual, you'll see they will specify "genuine" this or that. This is a means to get you to purchase their products. Most often there are alternatives.
You cannot use just any power steering fluid in your Honda. There are several manufacturers out there who make it, such as Prestone.
Honda genuine power steering fluid is different than other available choices. The formula is proprietary and not published. It was developed in the early 1990's to solve a significant chatter symptom in Honda power steering rack and pinon units. This problem was caused by incompatibility between the old fluid and the sliding seals on the rack sliding seals. It then became the go-to fluid for racks of other manufactures with similar symptoms. Others brands of fluids have caused leakage and chatter symptoms in Honda steering racks. It has a different blend of additives that are compatible with the elastomers (seals and hoses) used in Honda power steering systems. Some use it in all makes as it is said to be compatible with elastomers of all types.
Many vehicle makes use automatic transmission fluid for power steering system. This works most of the time but these fluids are optimized for clutch friction characteristics not sliding rubber seals.
The Prestone Synthetic Asian formulation power steering fluid for Honda is $6.99 for a 10 oz bottle at Walmart. I flushed my '06 Accord ps system with two bottles at 130K. Another few K and I'll flush it with another bottle. Also bought a case of DW-1 ATF for under $100. Drain and fill every 50K. Cheap insurance.
Never use other fluid than Genuine Honda power steering fluid. I'm being using Honda Accord 2.4 since brand new till now her age 11 Years, No problem towards my Power Steering pump or rack. It's proven to use Honda genuine parts or fluid for Power Steering, Transmission Oil, Engine oil, Brake oil may extend the life span of wear and tear parts.