Precious Bodily Fluids

[EuropaTC]

A good explanation of why all flat tappet engines aren't the same   

For my money, John has it spot on even before you count his practical experience to back up his logic.  I've used Mobil 1 in various grades since I got my car in the 80s. Initially 5/ or 10/50 IIRC, which was met at the time with cries of "but it will leak everywhere". (it didn't, or at least no more than usual)

xx/50 grade Mobil 1 isn't so common these days over here (although you can get it)  so I've been using 0/40 Mobil 1 in the Elan & Europa for a few years now. Makes zero difference to the oil pressure at any revs and for the mileages I do it's fine. As John says, the cams run in an oil bath and unless you've got very wide follower clearances it's likely to stay in place for months at a time, ready for your next start-up.

I think I've posted this chart before but can't recall where, so as it's relevant to this discussion here is the 2017 Mobil 1 Zn/P specs.

Brian

[surfguitar58]

Duly noted JB. That kind of experience goes a long way in my book, and your logic holds up quite nicely. As Gary t points out, there may be a bit of unjustified dogma about ZDDP out there. I guess I would counter by saying oil bath or not, we do have a sliding cam-on-flat-surface tappet design (metal-to-metal line contact) that was designed with understanding that zinc laced oil would be available, which was taken away for reasons having no regard for the welfare of our engines, and our engines are notorious for having lubrication issues (as dryly noted by this clown at minute 4:19 of this video: https://www.youtube.com/watch?v=bwoHmubxDIg ).

Call me a sucker for marketing hype, but the modest levels of ZDDP in Mobil 1 15W/50 are going to help me to sleep better, or at least let me stop worrying about my car and start worrying about being broke because I spent all my money on motor oil.

[jbcollier]

A good night's sleep... priceless.

Nothing wrong with using the V-twin stuff, just getting hard to find in certain locals.  Though that is about as a high a level of ZDDP (1750) as I would want to use in a street engine.  Too high a level of ZDDP and it gets be a detriment.

Some motorcycle engines had top end oil supply issues leading to cam and follower wear, all long before ZDDP levels were reduced.  Usually builders of these engines also pursue mods to get more oil to the top as well.  But, point well taken, higher ZDDP levels will help.

[surfguitar58]

For whatever it's worth, this was my question and response from the "ask Mobil" help desk:

"Question : Can I use 20W/50 Mobil 1 V-twin motorcycle oil in my flat tappet 1973 Lotus twin-cam engine (no catalytic converter)? It has the recommended viscosity rating, high zinc levels (1750 ppm ZDDP) and desireable Mobil 1 properties. My only concern would be the effects of whatever additives are included to enhance motorcycle wet clutch operation, otherwise it sounds like a perfect match. Please advise."

"I would not recommend using the Mobil 1 V-Twin, rather, I would consider using the Mobil 1 15W-50. It has a slightly lower amount of ZDDP (1300) but it still be about 30% over the recommended threshold for older engines with flat tappet valve trains.

Thank you for choosing Mobil,
Jake Ackerman
Mobil Help Desk Team Lead"

...and, with a totally contradictory opinion from the same help desk...

"Hello Tom,

This can be an excellent match for applications requiring an SAE 50 with high ZDDP content. Nothing about the fact that it is compatible with wet clutches will interfere with your engine’s performance.

Kind regards,
Luc LeBlanc

Americas Technical Help Desk
ExxonMobil Lubricants Technology
ExxonMobil Business Support Centre Canada ULC"

I guess Canadians are more open minded in their choice of lubrication.

[jbcollier]

The Canadian supplier is more relaxed because they no longer offer the V-Twin stuff in Canada.  Annoying.

[surfguitar58]

Naturally the super helpful Canadian advice guy told me my first choice oil was okay the SAME DAY my case of lesser oil arrived. 

[jbcollier]

Nothing wrong with the 15-50.  It only has a wee bit less ZDDP than the V-Twin and it is much easier to find.