What oil for a Rolls Merlin ?

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Before I get kicked off this board, yes, it's in a road going '55 Chev. Magazine article indicated that the oil is Penrite, and recommended for Harley's as the engines are similar [Confused] Penrite lists their HD motorcycle oil as a 50-70 (no W) Viscoscity @ 40 361 cst Viscoscity @ 100 32.1 cst Cold Cranking [email protected] -5C
 
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Isn't this the aircraft V12 that powered the WWII P51 Mustang? How could you get one of those in a car?
 

Shannow

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I read the article, and thought that there must be more suitable oils than a mineral based super thick non-friction modified oil for something so special.
 
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I once had a Rolls Canardly. It rolled down one hill and "can hardly" get up the next..... [Big Grin] I think the Merlin originally ran synthetic oil (in fact, that's why it was developed). I don't think it's necessary in that application though, because of the larger engine clearances and higher ambiant temps it's run in. I would stick with a high vis mineral oil.....with frequent changes.....
 
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quote:
Originally posted by TheLoneRanger: I think the Merlin originally ran synthetic oil (in fact, that's why it was developed).
I don't think that's accurate. The advent of jet engines with their very high operating temps were the impetus for the development of synthetic lubricating oil.
 
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The Germans used synthetic oil in their aircraft in WWII, as did the Allies, because of the extreme cold at the high altitudes. The Merlin was one of the most powerful fighter engines of its era, and flew at the higher altitudes where normal mineral oil would congeal. I read a theory once that the Merlin, as installed in the British Spitfire, was responsible for winning WWII. Because of the power and high service ceiling of the Spitfire, the Battle of Britan was won, and Germany was denied occupation of England. Without England as a land base, the U.S. could not have fought the European front as it did, and the war might have had a different outcome. Or at least would have lasted much longer. [ January 31, 2003, 03:13 PM: Message edited by: TheLoneRanger ]
 
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quote:
Originally posted by TheLoneRanger: The Germans used synthetic oil in their aircraft in WWII, as did the Allies, because of the extreme cold at the high altitudes.
I still don't think this is accurate. The temp at altitude would be irrelevant to an engine at operating temp. It's common knowledge that Germany had an active syn fuel and syn lubricant program going by the end of the war, largely because their supply of pertroleum products was completely cut off. Also, they had developed syn lubes for use in the ME 262 jet fighter. But as for the widespread use of syn lubes in conventional piston-driven aircraft engines, I've never read any mention of that anywhere. [ January 31, 2003, 03:36 PM: Message edited by: G-Man II ]
 
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I don't really care about who invented what and when, but wow , I want a ride in that machine. [Big Grin] [ January 31, 2003, 04:19 PM: Message edited by: Scott P ]
 

Al

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Amazing engine.Saved England in the Battle of Britain. Made by Rolls and Studabaker. Used in the Spitfire, Hurrricane, and the best airplane (probably) of WWII the P-51 Mustang. 1650 cu. in. 60 Degree 1650 cu. in. V12- Two Stage Blower. . Put out a max 1710 HP at 3000 rpm. Just in case you were curious [Big Grin] . I would think that a quality 40 wt would be fine. Piston speeds were not exceptionally high like the Allison V-12. It's not my engine though [Smile] BTW-the Germans did not have "synthetic oil" (I dont believe) The produced oil out of coal which was called their synthetic petroleum production. The U.S. I believe used Synthetic Oil first in 1948 (I believe) I know they did not use synthetic oil in the Merlin.
 
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quote:
Originally posted by Al: BTW-the Germans did not have "synthetic oil" (I dont believe) The produced oil out of coal which was called their synthetic petroleum production.
The Germans used the Fischer-Tropsch method, which converts coal gas into petroleum products such as gasoline, diesel fuel, and lubricant base stocks.
 
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All of the piston driven aircraft of that era used heavy straight weight low ash oils. Even the crop dusters of today using the radial Pratt & Whitney engines use 60 and 70 weight low ash oils. The reason for the low ash is to cut down on plug fowling. That would be the last thing you need in the middle of a dog fight. Since this engine is in that beautiful 55 and will never again see sustained high rpm's, and dog fights, I would think a good high grade straight 50 weight would do just fine. You will need the detergents to keep the insides clean while it just putts around in parades and car shows.
 
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About the Germans: You are both correct. They used Fischer Tropsch to make large amounts of petroleum fractions for their economy. This process is often called "coal liquefication" And is often called "synthetic" oil production (which I consider a bit of a misnomer). BUT, they also pioneered the use of PAO synthetics motor oils, due to the demands of winter operations on the eastern front. Fred... [Smile]
 

Jay

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I thought aviation engines had to use non-detergent oils. In fact, I thought engines had to be specifically designed to work with detergent oils. That's why, even today, piston aircraft engine oils are non-detergent. The engines aren't designed to work with detergent oils. My vote is to use a good aircraft engine oil. [ February 02, 2003, 09:56 PM: Message edited by: Jay ]
 
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quote:
Originally posted by Jay: I thought aviation engines had to use non-detergent oils. In fact, I thought engines had to be specifically designed to work with detergent oils. That's why, even today, piston aircraft engine oils are non-detergent. The engines aren't designed to work with detergent oils. My vote is to use a good aircraft engine oil.
The only reason piston-driven aircraft engines use non (or low) detergent oils is to prevent the deposits that result when the additives burn from fouling the sparkplugs.
 
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Retired | Wausau, WI
Yep, as long as this 55 is driven on the ground, use a good detergent oil. But if it sprouts wings, put some AEROSHELL in it. By the way, most piston engine aircraft engine oils today have some detergents in them in a limited amount, but they are loaded with dispersents.
 
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i would check with someone in the know with this engine. in aircraft engines, non-AD oils will cause not only damage to the bearings, but will eventually cause RSI (runaway surface ignition), followed by the pistons draining out the exhaust pipe. since this engine is liquid cooled, it may not have that problem, but the bearings may not be compatible with the additives in automotive oils. best choice until you find out would be straight weight mineral oil (aviation break-in oil). talk to some drag boat people, these engines are popular with them, or call shell or mobil.
 

Shannow

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Update, on the Harley Davidson rated 50W-70 oil in the Merlin. I caught up with a mate I'd not seen for ages, and asked how his tank collection was going (he had 1 1/2 Matilda tanks last time I'd seen him). He's now purchased a couple of Centurion tanks, which are fitted with meteor engines (Merlins sans superchargers). The advice he got from three of tha major oil suppliers down here was "SAE30 4 stroke lawn mower oil". So what's so special about an SF rated oil that gets (at best) changed every year (or never) ?
 
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