Engine Oil Recommendations 8-105

More
23 Jan 2017 18:40 #32323 by RandyEma
RandyEma replied the topic: Engine Oil Recommendations 8-105
I have been using a 40 winter or 50 summer with a zinc added. R

Please Log in or Create an account to join the conversation.

More
23 Mar 2017 23:05 - 23 Mar 2017 23:39 #32712 by HELMUT.HUBER
HELMUT.HUBER replied the topic: Engine Oil Recommendations 8-105
Well, I am not a technician, but I remember a very good article on engine oil some years ago in the ACD N/L - written by an experienced Cord 810 owner; his record includes the results of "don'ts", too, which makes it so convincing. By the way, technician friends, who are tinkering around with classic cars since the 1960s, have deemed the point of this story very plausible.
This essay stated that engines without a filter in the main feed of the oil pump, which cleans ALL the oil in each circulation run, ALWAYS should run on low-tech, single-grade lubricants. The reason is that these oils tend to produce fall-out in the sump, composed of zoot and the occasional grit. By the way, "sump" and the German word for swamp are very closely related, you can imagine why. This is the intended way of preventing dirt remaining in circulation, grinding out all the bearings in short time. Naturally, this system relies on regular sump cleaning, and you also should respect the oil change recommendations you find in your 1930 owner's manual! If you use multi-grade, modern, high-detergent oil in a filterless engine (the bypass filters of Lycoming's inline 8s are of very low efficacy in this respect) you not only run in trouble because the oil simply won't get hot enough to reach a higher viscosity grade, but this kind of oil also drags along all the dirt which results from a live engine and does NOT drop these abrasives in the sump. This results in premature bearing wear, and you can imagine the rest (and prepare a healthy sum for a thorough engine overhaul).
The club member, who wrote this essay, had used "modern" lubricants on his freshly made engine only to find that it was in for another stint at the workshop with run-down bearings after only 10.000 miles. After this repair he only used a simple SAE 30 or 40 oil, and had a sound engine for more than 70.000 miles, still counting when he wrote the paper.
I've always used SAE 30 on my Lycoming, which gives stable oil pressure also in hot weather; a 40 might not be wrong, either (my 1936 Triumph Gloria is quite happy with this grade). Some few additives, which retain lubrification under difficult and borderline conditions, might be a good idea, but beware of the detergents typical of modern engine oils, unless you have done a major rebuild of the engine incorporating a modern filter in the main oil path - and this is a questionable step, I'd say...
And for the viscosity vs. temperature issue: I used a FIAT Ritmo 105 as my regular transport in the 1980s; this car had ample instrumentation, including oil pressure and temp. gauges (and a beautiful dohc engine, very similar to the classic ALFA Romeo four originating from the 1950s). When I used common 15-50 oil, I always noted a slight drop in oil pressure in the higher rev range; only if I drove the car at very high speed (well, 100 mph) for a longer time, the oil temp. rose over 100°C - and oil pressure went up again! As i could reach this state only on the German Autobahn, but not at home in Austria (where we got a 80 mph limit on the highways), I switched to a modern-type SAE 30 and from then on had stable oil pressure under all conditions.
Last Edit: 23 Mar 2017 23:39 by HELMUT.HUBER.
The following user(s) said Thank You: 1748 S

Please Log in or Create an account to join the conversation.

Time to create page: 0.058 seconds
Powered by Kunena Forum