Which Oil is Best for the Y Block Ford Engine?

Over the past two decades Shell Rotella 15w-40 has been popular, but what changed?

Why be Concerned about Oil?

Even more critical than coolant is the lifeblood of any engine - oil. Every engine needs some type of lubrication. In the typical 4 cycle gasoline engine there are many moving parts. These parts are made of metal. Metal sliding and rubbing against metal creates friction. Friction creates heat and wears the metal. Long story short - the Y Block, like every other engine, needs oil.

Over the past few decades, much has been written, published, and suggested concerning motor oil for flat tappet camshaft engines. While most every automobile engine up to the present day will have a set of crankshaft and rod bearings that need specific clearances, an engine with a flat tappet camshaft will have specific needs of lubrication. The lobes of flat tappet camshafts slide against the face of lifters with each opening and closing of each valve. Increase the valve spring pressure with high performance packages and the risk of camshaft failure heightens if not using the right oil.

In addition to camshaft lobes and lifter faces, other valve train parts need lubrication also.

Rocker arm tips on the Y Block are known to show their wear over the miles of run time.

In addition to the lifter faces and camshaft lobes would be the valve train parts. The Y Block has rocker arms that are mounted on a common shaft. That shaft fills with oil and lubricates each rocker arm. The rocker arms have two weep holes - one for the tip and valve stem and one that will send oil down the line of the push rod.

OEM rocker arm design was critical to top end oiling as metal rides against metal.

All that being said, what is needed in an oil to lubricate the critical components of the Y Block Ford V8 engine? The main additive that is required in a typical motor oil is ZDDP. That is Zinc Dialkyl Dithiosphosphate. Many people in the industry will shorten that to say "Zinc" when referring to ZDDP. For decades this was not a problem for Y Blocks. Most any common motor oil off the shelf included 1200-1500 parts per million of ZDDP and therefore gave good lubrication to all flat tappet camshafts.

A little more than 20 years ago the motor oil additive packages across the industry changed dramatically as ZDDP was almost completely dropped from many motor oil lines. Thousands of owners of classic cars scrambled to find a substitute with many turning to diesel engine oil that, even with the industry changes, had kept ZDDP in its additive package. For quite some time now, Shell Rotella 15W-40 has been a fan favorite of quite a few Y Block owners. Also, at the time the oil industry changed, ZDDP additives gained very quick popularity and still remain on parts store shelves today.

ZDDP additives are still quite popular today for those running flat tappet camshafts.

So, what are the recommendations in the modern era? First the good news. There are many different oil companies that have gone back to manufacturing oil that contains the ZDDP levels needed for flat tappet camshaft engines. A good rule of thumb for engines with stock valve spring pressures would be 1200 ppm of ZDDP and maybe a few hundred more if a high performance engine. For those that still want to run Rotella, be advised that the detergent levels are now high enough to actually offset the ZDDP benefit from this oil. A good video from the YouTube channel, The Motor Oil Geek, explains this quite well.

Additionally, the link below is for a video that I recently published to my YouTube channel, @HotRodReverend, that lists the issues and gives a few recommendations. It is certainly not as bad as it used to be. Any motor oil with an API rating of SP (starburst on the back of the bottle) has at least 1000 ppm of ZDDP. For stock Y Blocks this is just fine. If you want a little more insurance, an additive will help take care of that anxiety of course.

Many people ask me about what weight of oil to run in a Y Block. Much of this will depend upon bearing clearances and climate where you live. Ford originally recommended a 20W or 30W oil in the Y Block. These days, a lot of us are using a 10W-30 or 10W-40 oil and get along just fine. As my video shows, checking the rocker arms, lifters and cam lobes, and main bearings has shown that my choice has only given positive results after thousands of miles and much abuse.

In closing, do some homework, research, and study up a little bit before choosing your motor oil for the Y Block. However, do not get overly concerned these days as many motor oils are going to be just fine right off the shelf!

The Hot Rod Reverend

aka Daniel Jessup