What kind of oil should I use / what is the "best" oil?

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Mike Horton
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Re: What kind of oil should I use / what is the "best" oil?

#181 Post by Mike Horton » Fri Mar 27, 2020 8:58 am

There is a "sticky" on oils on the 912 registry BBS, and like our David Jones, a retired petroleum fuels blender, who got me on track on the compromise jetting for the ... uh ... PC 10% ethanol fuels, a 912 owner from Australia, Richard Michell, also a retired petroleum professional, has written a book on "Which Oil", on choosing the right oils and greases for your antique, vintage, classic or collector car, the content facts of which parallel the history, and needs of which i observed in my 5 decade experience with aviation air, fuel, and oil cooled engines. Published by Veloce Publishing, find it, and learn more fact, on oils, etc., a worthy investment of research time, in this quarantine period in our history.

Richard has also just completed a DIY overhaul, on his 912 engine, and is in the break in process now,

Mike
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David Jones
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Re: What kind of oil should I use / what is the "best" oil?

#182 Post by David Jones » Fri Mar 27, 2020 10:32 am

As it happens I am in the break in process of my recently rebuilt original engine in my 1959 "A" coupe. So far about 300 miles on Shell Rotella and at 500 I will change oil then after another 1500 switch to 15/50 synthetic. Engine was run on the floor for about an hour before going in the car. At a steady 60 mph and running through the gears so far it has not gone over a needles width over the left green portion of the temp gauge so it has never got really hot yet but the weather has not either. Waiting for the oil change to open it up to full throttle. Only real upgrade was a set of big bore P&C's.
If I had known I would live this long I would have pushed the envelope a little harder.
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Pete Indelicato
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Re: What kind of oil should I use / what is the "best" oil?

#183 Post by Pete Indelicato » Thu Apr 16, 2020 10:48 pm

Quaker State 10-40, great for hot CA summers.
1963 T6 couple #212891, motor #*KD*P*730464

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Re: What kind of oil should I use / what is the "best" oil?

#184 Post by Bill Romano » Thu Apr 23, 2020 4:57 pm

Good grief ... the latest comment is dated mid year 2011 ... I'm using a Precision Matters full-flow oil filter on my 64C engine with Mobil 1 oil ... have I doomed my engine? I also still have the original filter in place since I didn't see any reason to get rid of it and the engine doesn't look right without it. Any modern day thoughts?
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Re: What kind of oil should I use / what is the "best" oil?

#185 Post by Bill Romano » Thu Apr 23, 2020 5:03 pm

Umm.... As soon as I posted my question (#184) some 2020 comments appeared ... I didn't notice these when I looked through the permanent "sticky" topics in the Main Discussion Forum. Careless or just blind?
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Graeme Langford
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Re: What kind of oil should I use / what is the "best" oil?

#186 Post by Graeme Langford » Tue Jul 07, 2020 5:49 pm

I am new to the Porsche 356 world having just purchased an A coupe. It had a full service and they used Porsche Classic Motor Oil 20w/50
1958 356A
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Re: What kind of oil should I use / what is the "best" oil?

#187 Post by David Jones » Tue Jul 07, 2020 6:58 pm

I hope you did not have to foot the bill. I use mobil 1 15/50 synthetic and change it at 4k miles. Change filter every other oil change.
If I had known I would live this long I would have pushed the envelope a little harder.
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Re: What kind of oil should I use / what is the "best" oil?

#188 Post by Douglas Madsen » Wed Jul 08, 2020 6:35 am

My engine, for the last 100,000 miles, ran on Mobil 1 15/50. I changed the oil and filter every 2,000 miles. I just had the engine rebuilt due to wear indications (shiny debris at oil change). I now have new p/c, and I am using the existing scat crank, which had no measurable wear after 150,000 miles.

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Re: What kind of oil should I use / what is the "best" oil?

#189 Post by neilbardsley » Tue Aug 04, 2020 11:33 am

You might be interested in this chaps analysis Mobil 1 didn't make it out of the first round :)

https://youtu.be/TWuKvnCq1js

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Re: What kind of oil should I use / what is the "best" oil?

#190 Post by David Jones » Tue Aug 04, 2020 1:42 pm

Neil, this analysis is of 5/30 oils and all have very low levels of ZDDP which because of the age of our engines is an essential wear additive. In addition that multigrade viscosity is not adequate for parts of the world where summer temps at or above 30*C or 80 *F temps are common. A 30 weight oil would not be viscous enough to maintain good oil pressures much of the time. I grant you that back when our cars were new a 30 weight oil was considered adequate for summer use but Porsche also warned against multi viscosity oils back then and recommended a flush with a new oil if you switched brands before refilling after an oil change. We should be mindful of the advances made in oil technology because if you used the recommendations in existence for our engines in the 50's and 60's you could damage your engines. A modern 5/30 oil designed for an engine that was built for an energy conserving oil is unlikely to be a good choice for a 356 engine. It is an unfortunate fact of life that oil companies use marketing to promote their products not oil company engineers so be very wary of claims that may not be all they seem and often it is by no means the fault of the person writing the review especially if that person is only publishing reports he has commissioned and not done the actual work. Actual experience is a far better recommendation to me than lab reports though the lab reports can and do provide very useful information. Bottom line to me is that the oil must contain at a minimum 1100 ppm ZDDP and a lower viscosity of 15 (10 if I am pushed) and a high of at least 40 and for me preferably 50 because I have a heavy right foot and I like the extra viscosity for those really hot days over 38*C and 100*F.
My opinions are based on personal experience and a little bit of professional experience in the oil industry. Read all you can about any oil you consider using before buying and check it frequently and change it according to your driving style.
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Re: What kind of oil should I use / what is the "best" oil?

#191 Post by Tom Wavrin » Tue Aug 04, 2020 7:27 pm

I previously had used Amsoil's high zinc, high TBN, ester-based 10W/40 since break-in several years ago. Engine temps were OK even with ambient temps at 95 -100*F. I changed to Mobil-1 15W/50 upon David's recommendation, the considerable cost saving and Mobil being a major vs boutique brand. The 15W/50 does have a downside for me because the engine does run cooler during wintertime driving when ambient temps typically are in the 30 - 45*F range.
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Re: What kind of oil should I use / what is the "best" oil?

#192 Post by neilbardsley » Wed Aug 05, 2020 5:35 pm

David has it ever been above 38c in Wales? Thank you for your advice.

When I look at an oil I look at the viscosity index and flash point. Aren't they better indicators of performance at higher temperatures? In the video he also does a 400f evaporation test and lubrication test post 400f.

Ps currently using full synthetic 5/30 with 1100 zdpp. Will change to 10/40 on your advice

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Re: What kind of oil should I use / what is the "best" oil?

#193 Post by David Jones » Wed Aug 05, 2020 7:24 pm

Neil, for normal UK weather that is to me an acceptable choice but when the temps go over 100*F I would be going easy on the gas pedal if the temp gauge looks like it is rising past mid scale. I like synthetics for many reasons but one in particular makes it suitable for a 356 and that is its high coefficient of heat transfer. Read the below for more info than you really need.

Effects of engine operation on the lubricating oil used in it determine to a large extent the ability of the oil to maintain continuous lubrication and, consequently, of the engine to function efficiently. Engine operation has three major effects on the oil: (a) complete destruction of part of the oil, (b) physical and chemical changes in the oil and (c) contamination of the oil by foreign matter.
Oil is not worn out by friction but is destroyed by burning or decomposition caused by exposure to the intense heat of fuel combustion in the cylinders or the metallic parts of the combustion-chamber. The quantity so destroyed depends upon (a) fuel-combustion temperatures, (b) temperatures of the metallic parts, (c) quantity of oil exposed to these temperatures, (d) length of time of such exposure, and (e) volatility of the oil.
The quantity of oil that is exposed to the destructive temperatures, and thus consumed, depends upon the mechanical condition of the engine, the operating conditions and the viscosity of the oil. With the splash system of cylinder lubrication an excess of oil is supplied, some of which passes above the piston-rings and spreads over the tops of the pistons, the combustion-chamber walls and the valve heads, where it is constantly exposed to the flame of combustion and is destroyed. Oil on the cylinder-walls is covered by the piston-skirts part of the time and is renewed at every piston-stroke, hence less oil destruction occurs there. The common practice of using an oil of high viscosity to reduce leakage past the piston-rings, thereby decreasing the oil consumption, may easily be carried too far and result in inadequate lubrication of the upper cylinder-walls and consequent excessive wear there. With an engine running at 1000 r.p.m., the duration of the power-stroke is approximately 1/2000 min., or 1/33 sec., during which brief interval only a small portion of the oil on the cylinder-walls can be destroyed.
Lubricating oil must be converted into a gas before it can burn, hence its volatility is important. The flash-test, however, is of little value and may be misleading in determining volatility, as it does not indicate the volatility of the entire mass. Straight-run oils composed of a narrow range of fractions from crude petroleum and having a straight distillation-curve may show a slightly lower flash-point than a blended oil, yet contain a smaller total quantity of the more volatile fractions than an oil having a higher flash-point and hence will have greater ability to resist heat.
Ordinary temperature changes do not permanently alter the viscosity of an oil but the specific viscosity is changed by relatively high temperature and by contamination. Distribution of oil to the bearing surfaces, ability of the oil to maintain complete separation of the surfaces, internal friction or resistance of the oil to motion and effectiveness of the oil as a piston seal are all functions of its viscosity; therefore changes in viscosity are of importance. These are caused by gradual consumption of the lighter fractions by oxidation and cracking and by the admixture of water, unburned fuel, carbon, dust and metallic particles.
The excessive quantity of fuel used when starting and warming-up a cold engine is the principal cause of dilution by fuel, water contamination is due to cold surfaces in the crankcase that condense the water vapor of combustion, dust enters the engine through the carbureter and breather-pipe and metallic particles wear off of the bearing surfaces most rapidly when wearing-in a new engine. Contamination by fuel reduces the viscosity of the oil, water forms an emulsion and, with carbon, dust and metallic particles, forms a sludge. All of these conditions are likely to have deleterious effects on the engine.
If I had known I would live this long I would have pushed the envelope a little harder.
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Graeme Langford
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Re: What kind of oil should I use / what is the "best" oil?

#194 Post by Graeme Langford » Sun Aug 09, 2020 4:35 pm

any thoughts on using the Porsche Classic Motor Oil 20W-50. I believe it is a mineral based oil. I would hope that it contains a good level of zdpp
1958 356A
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Re: What kind of oil should I use / what is the "best" oil?

#195 Post by David Jones » Sun Aug 09, 2020 5:18 pm

Graeme, I have not tried it but I am sure it will perform well. I cannot see any reason to try it though when there are other choices just as good that can be bought anywhere for less cost. Because it has the Porsche name on it does not mean it is better. When Porsche refines and blends its own oil I may try it.
If I had known I would live this long I would have pushed the envelope a little harder.
Cymru am byth
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