The following was a recent topic on SmokStak, which can be found on the Internet at: www.engineads.com/smokstak.cgi. As ever, various individuals started, commented on and concluded the following bulletin board thread.
What's the best bearing grease?
I'd just like to know what you guys use for grease on your main bearings. The grease I'm currently using is too thin and the bearings heat up. I believe the grease is just being flung out of the bearings. And no, the bearings are not too tight, they have three to four thousandths clearance. Thanks in advance for any advice. - Andy
Andy, I use the same grease I use for my big truck. It's Retinax by Shell; a good, heavy red grease. I've never had the problem you're having, but if you're running them for long periods of time and they are getting slightly warm, that's normal. - Mark
The lithium grease they use on front wheel bearings for cars with disc brakes will take the heat, and keep the bearings lubed. You can get it at any parts store. -Chuck
You might want to try Lucas grease. It is sticky and won't fling itself all over your engine. It also stands up well to heat. It is used in a lot of big trucks and in race cars. - Mike
I may be wrong, but Kendall blue grease is about the only one left that is entirely petroleum based, not soap based. - Bob
I have found that if I have a question about lubricants I call our local commercial lubricant dealer. Most of them will sell a case of grease to anyone. They will also be happy to give technical information as to temperature range, rotational or longitudinal speed, clearances, etc., and what would be the best grease for an application. They normally get a big thrill out of helping us figure out what will work best in these old engines and tractors.
I sent down Rumely lubricant data sheets on suggested lubricants for their engines and transmissions. After a few days our local Mobil lubricants dealer reported back to me that they had found comparable lubricants for all of Rumely's recommended oils. They cross-referenced a 60 weight engine oil that is made for use in kerosene burning engines. This oil is the same as Rumely's original oil of 80 years ago. There is one jet engine that still requires the same oil. They were even able to find thermal transfer oil for the radiator of the same viscosity and additives as originally required by Rumely. If they ask what company you are with, tell them it is 'your name restorations,' or something like that, and pay in cash.
One thing to remember: As the last poster said, most of today's greases are soap based, and Rule #1 is never mix soap types. This means don't mix red grease with white grease, black grease, blue, green or whatever. Clean your application thoroughly before using a different type of grease. - Mark
Seems like one of the owner's manuals for Hercules engines said 'Do Not Use Axle grease.' It also seems that's what we're all using now, as that's all that's readily available. I would like to find some of the old yellow paraffin-based low melting point grease that was used way back when. - Bob
Just a few thoughts on grease. Today's wheel bearing greases are optimum for ball bearings. They work best in very thin films and in that application are very effective. If you are lubricating a wagon axle, any grease will work fine. Moly greases are very good in slow speed applications where the clearances are 0.002-inch to 0.005-inch.
As you know, the moly works into the metal surfaces and provides enhanced lubrication when there is the potential for metal-to-metal contact. The reason moly is not recommended for ball bearings is because the moly can build up on bearing race surfaces and reduce bearing clearances enough to cause bearing failure. Some years back the Model A Ford club recommended a moly grease for rear axle ball bearings. A rash of axle bearing failures followed, which were traced to moly build-up on the races. It is in fact an irregular build-up of the moly and forms patches on the races, and it had the same effect as dirt in the bearing. So don't use moly or any moly additive on any ball or roller bearing application. This includes transmissions, too.
On the other hand, there are real benefits to using moly grease on our engines, since most bearings are operating with 0.003-inch to 0.005-inch clearances and the moly will protect the bearing and shaft with a molecular coating of moly.
Lubriplate makes a moly grease used for construction machines and other types of exposed gears and bearings. It is tacky and will not spray out of bearings or off of open gears. It is called No. 3000 Heavy Duty Tacky Moly Grease (part # 10108-098). A large tube costs about $3.50 and can be found at any bearing supply house or construction machine supplier. This grease is black, soft and very sticky. - Sherm
Andy, I use this grease, I bought a five-pound can at a surplus shop. It works very well for me. It's a 'short' grease and it stays in place. When you use long-threaded grease it works itself out the bearings. The following text goes with the grease. 'Aero Shell Grease 14 is the leading multipurpose helicopter grease used for most helicopter main and tail rotor bearings (where specified). It is made with mineral base oil and a calcium soap thickener, which provides outstanding protection against moisture, corrosion and fretting. It has a useful temperature range of -65 F (-54 C) to +200 F (+93 C). Aero Shell Grease 14 is qualified under MIL-G-25537C specification.' - Sixm John
Thanks for all the advice, guys. Would have thanked you sooner, but the computer caught a bug. - Andy
All the engines I've restored have had various hunks of bad stuff in the bottom of the grease cups. This stuff is old, hardened grease mixed with dirt, sawdust or whatever was in the environment the old engine worked in. Keep in mind that many of these engines worked through the Depression, when food on the table might have been more important than oil or grease for the engine. Many of them ran without the daily or hourly lube job you see happening at our engine shows. Clean the grease cups, right down to the bottom, and run a cleaning stick through the bottom hole. Your engine restoration will last longer without the dirt in the bearings, no matter what your choice of grease. - Harry
'Seems like one of the owner's manuals for Hercules engines said 'Do Not Use Axle Grease.''
SmokStak is an engine conversation bulletin board and is part of the Old Engine series of Web sites that started in 1995 as 'Harry's Old Engine.' Harry Matthews is a retired electronic engineer and gas engine collector from Oswego, N.Y., now residing in Sarasota, Fla.