How dirty does your oil get?

[M Penta]

I have changed mine 2x now. 1st was just to run it/flush it after prolonged storage, now using 20W50 Valvoline racing oil and have about 400 miles on it. It no longer looks like new and is a bit darker now. Not sure if I should change it again before heading on a 500 mile round trip to Limerock. How does your oil look at say a 1000 mile change interval?

Also, what change interval do you prefer with non synthetic oil? At $45 per change (with filter) it is not a huge expense, but not something I want to do every 500 miles.

Thanks,

Mark

[George Walling]

Mark, Here is what I do when my engine was rebuilt I changed it and filter at 100 miles checked valves and timing then at 500 miles changed oil and filter checked valve adjustment and now I change it and filter along with checking and adjusting valves as needed. I'm using 20/50 Castrol non synthetic oil. I know this maybe over kill to some but oil/filter and checking valves are keeper than rebuilding engines. Hope this helps and enjoy your car.

George

[David Jones]

I have Shell Rotella 15/40 conventional oil in my 64C engine and about 1500 miles on it since changing the oil and it is light brown. I will change it at 3,000 and change the filter at 6K. Cost about $40 for 2 oil changes if you factor in a filter every 6K.
The engine in my 59 coupe which has a full flow filter burns a lot because of worn rings and goes dark very quickly but I also use synthetic because it has high miles but oil changes are out of the question as it is coming down this winter and the original engine is going back in.
When using Mobil 1 15/50 synthetic on the old engine in the 64 before rebuild I ran 5k between oil changes but also changed the filter at same time.

[M Penta]

Thanks for the info.

George, I did similar with my engine. I don't think it is overkill at all.

David, I have read some of your posts on this. I am considering using the Rotella 15W40 since I always have it on hand for other vehicles and have used it for many years. I don't think I will go synthetic since I plan to change the oil often (I do not have a full flow filter, maybe someday). I purchased another 5 qts of 20W50 Valvoline racing today for $35, at the same store they had 5qt jug 15W40 Rotella on sale for like 14 bucks.

Not an area I want to pinch pennies, but I would like to keep the CC clean. Seems like once it gets dark, it will always be dark with out another thorough flush (or two or three!). maybe I should use the Rotella and change it very frequently, filter every other time.

Also, I should mention that I replaced the valve springs and rocker asm's. The oil was new when I did the job and everything was installed very clean, but might as well just change it again just incase, and check sump screen one more time.

I spent almost $200 today on supplies for engine oil changes on 3 of my cars, and some gear oil. Seems like the price of oil went way up went fuel was high, but never came back down!

[David Jones]

Mark, when I was racing F Vee using a VW 1200 cc engine tuned to run at 7K rpm I always used synthetic after I found that conventional oil oxidized very quickly at anything over 250 degrees F. Synthetic would still look clean even after a full race distance at over 270*F and did not smell burnt like conventional oil. I also never changed oil or filter during the season unless I had to tear the engine down for some resin. Failures of 50 year old parts were not uncommon. I had one race engine that I won a race with at Mid Ohio and that engine had 22 races on it. That amounted to a whole season of racing and it went on past 30 races when I sold the race car.
When I started racing Vee, Castrol GTX was one of the most used oils and that we would change every other race. The rod bearings were shot after 6 races. With synthetic the limit was the fall off in engine performance usually caused mainly by valve seat wear.

[M Penta]

Wow, interesting.

Anything different with the ZDDP levels in the synthetic oil? After reading the long discussion on oils, I was even more confused so decided on the 20W50 Valvoline racing since they had it at Autozone. But I value your extensive experience based on vintage racing the vee's so am considering going synthetic after all. I just do not want it to leak!

Would the 5W40 synthetic Rotella be a better option then the conventional 15W40? I use the 5W40 in my old TDI with 275K which uses no oil and has original turbo. It gets dark instantly after a change but that is just the nature of an old diesel. I also like to use it in my tractor in the winter as well. I can buy a 5 gallon can of it and feed it to several vehicles at a reasonable cost.

I probably should not start another lengthy oil topic, but almost too much info/opinion in the other one. I am most interested in what the vintage racer use.

'EDIT' After reading up more on the Synthetic 5W40 in a 356 this seems like a good way to go, but synthetic 15W40 Motorcycle oil probably best? More research required, but I am strongly considering synthetic now. The sting of my oil bill today has passed, and for roughly the same price as the Valvoline racing I can use synthetic anyway.
I have come to my senses that these engines are too valuable to worry about frequent changes with synthetic oil. Cost of doing business...
My main concern was leaks and consumption with synthetic oil, one way to find out.

Mark

[George Walling]

Mark, I add 4 oz of ZDDP to my Castrol 20/50 in my Speedster and also to the 10/40 Chevron Supreme oil in my 65 Ford Falcon. I have seen several engines in American cars go south from lack of enough ZDDP so just for piece of mind I run in all my classic cars. I do have a 2016 Dodge Ram with the 6.4 Hemi that I run the synthetic 0w/40 as it is recommended by Mother Mopar. So I think some of the darkness occurring in your engine oil is more than likely coming from the oil cooler and long storage just my thought. I would also say it is your car and do as you feel and trust. Good Luck.

[M Penta]

Perhaps, but I may be over stating the darkness. It looks just a bit darker then new at 500 miles but I would like it to stay that way. Thanks for the tip on the can of ZDDP, was not aware this existed.

I have a 66 Dodge which I have been using Rotella 15W40. I never worry much about that old slant 6, but I should not take her reliability for granted!

I am considering buying a 5 gallon pail of Synthetic 5W40. I can use it in Dodge, 356 and my Jetta Tdi, not to mention 2 tractors, multiple go carts, mowers etc! Maybe even my wifes Jeep Wrangler but I will need to check on that...

It sure would be nice to have a single oil on hand, with a proper pump on a large, sealed pail.

Thanks,

Mark

[Neil Bardsley]

I used to use 20W50 Valvoline racing oil in my 356 (built in 2002ish by Harry) but at the last oil changed I tried a full synthetic 5w/30. However, I've been losing some oil from the engine. I believe via the seals. Michael Horton, on here, talks about the synthetic oil getting past old seals. I think that at 15 years old my seals qualify. I'm going to try the 20w/50 again and see if the leaking stops. However, the synthetic oil does run a lot cleaner and, perhaps, a little cooler. There is an readily available synthetic, in the UK, that also has good zinc levels.

https://www.ebay.co.uk/i/192049087705?c ... 625&crdt=0

[David Jones]

I got in to the petroleum industry in 74 when I came out of the RAF and though I never specialized in lubricants I worked closely with many manufacturers formulating oils because I specialized in measuring oil and fuel parameters. It is my belief because of my exposure that for a Porsche 356 engine and indeed VW engines a minimum level of around 0.11% ZDDP is required to maintain valve train integrity between scheduled oil changes. One thing I do believe is that all of the oils used for diesel engine use have two commonalities. High ZDDP levels and higher summer weights for multigrade use . e.g.; 15/40 or 15/50 or even 10/40 which is my choice of weight to use.
Remember diesel oils are not subject to the ZDDP restrictions imposed on gasoline engine oils because there are no catalytic converters on diesels that will get poisoned over time by the ZDDP.
I also use oil filters designed for diesel engine use in preference to others because of the higher pressures and and stresses involved.
Check out the L&N website for a discussion on oils if you want to get thoroughly confused.http://support.lnengineering.com/2014/0 ... otor-oils/

[Mike Horton]

Neil, for a little clarity, and as George mentioned above, I suspect the dark color Mark is experiencing, is from the long storage, and not knowing the engine's history, it may also have a build up of carbon, and other contaminates, from a lot of miles. In such cases, I like to do a flushing change or 3 with an additive like Marvel Mystery Oil, Bardahl, or other product designed to help flush built up old contaminates, which are built up, in an engine. I once did this in an old Ford P/U by changing the oil with the old HD Texaco Havoline, in straight 30 wt., every 1,000 miles, until it cleaned up. When I finally tore it down for overhaul, there was a streak in the center of the oil pan, to the drain plug, which was cleaned down to a bare new metal color.

Another issue, which adds to the leakage of older 616 engines, is not having the complete, and correct for the year, factory breather system, either the old through 356B open draft tube system, or, from the 356C engines, the closed system, which must draw through the right side carburetor, looking from the rear of the car. On the closed systems, if this is not done, especially on a higher mileage, more worn, engine, the crankcase will pressurize, and the resulting internal pressure, will literally blow the oil out through any weak gasket, or other path.

I am in agreement with David, being an astute student of all he has written, of the use of the thicker weights, and non-synthetic oils, though, the more modern semi-synthetics, don't seem to be as bad, but, years ago, I had some severe cam/tappet/valve tips/rocker arm toes, in a very expensive high altitude turbocharged, F/I high altitude high performance cabin class twin engined corporate airplane, due to running a straight synthetic, though the oil was not FAA approved for use in aircraft, and my judgement back then, was the oil didn't have the ability to absorb, and contain the heat of combustion, and to be able to carry it out to the air cooling designed into the plane. Since then, I've only run synthetic in my water cooled engines.

I was taught by my mentor, that these engines are not only air cooled, but fuel, and oil cooled, as well. I have specific stories in 616 engined 356s, & my 912, to support these theories. Full flow filtering is a serious advancement, I use a Pre-Mat remote, and choose not to exceed 2,000 miles, if I'm not using my car daily, which I did when commuting in it, for 18,000 ish miles.

Neil, my feeling is that your 5W30, is way too thin, and a switch back to either the Valvoline Racing (adequate ZDDP), also available in a straight 30 wt., or something like David's 15W40, a weight I have used, and really like, but do your due diligence, as the diesel oils, are best typically, when they meet the older, pre low sulfur blends. I have also successfully used the 15W40 Shell Rotella T, and there is a 15W40 CHEVRON DELO 400LE Diesel Oil, conventional as well, which meets the minimum ZDDP needed for protection, of the highly loaded metal part$... my $.02

[Jeffrey Leeds]

Our resident academic, who resides in the ivory tower, advises Mobil 1 V-Twin air cooled motorcycle oil (20-50). It is an SJ API approval oil, which goes back to the days that motor oil actually had muscles (the Phosphorous and ZDDP additives for this product are nominally 45% and 35% greater than in Mobil's turbo diesel oil).

Mobil 1's Product Data Sheet provides interesting information for those who are so interested in this stuff:
https://mobiloil.com/~/media/amer/us/pv ... -guide.pdf

[David Jones]

If you want to clean all the old sludge out of an engine I have used a 50/50 mix of ATF and straight 30 wt. I do not drive the car so I do not put any load on it but run it for maybe 30 minutes at normal or slightly higher idle. After that I drain it and refill with whatever oil I am using. Unless the engine has been badly neglected that is usually sufficient to clean it up.
I do agree that 5/40 or a bottom weight lower than 10 is a little on the thin side. That would only be necessary if you drive in cold temps way below freezing which most of us do not do any more. It was arduous back in the day with the worthless heater so why put yourself through that misery in this century.
A 20/40 is recommended down to 0*F and I for one will probably never take any of my 356's out in that temperature unless my other modern cars are dead because of an EMP burst. I feel that 10/40 is as low as I ever need to go but prefer the 15/40 or 15/50 as I can be fairly sure that has enough ZDDP for my flat tappet needs.

[M Penta]

Great info, I value your opinions and appreciate the thoughtful replies. This is a very good condensed version of the other oil discussions.

Jeffrey, yes the Mobil1 V twin 20W50 appears to be the ultimate choice. $10 qt OK if I can go 2000+ miles with it. Probably worth the extra few bucks a QT over the conventional Valvoline 20W50 racing oil.

Anyway, I have learned a lot about oil the past few days and am now better informed to make the right choice. I like the idea of having one oil for multiple vehicles, but should not make compromises based on convenience. One thing I have decided is to just change the oil again before driving to Limerock, if for nothing else peace of mind.

As for the engine, it is the 912 "mystery" engine with S90 heads in my 64C. I have little info on the history of it, it appears to be freshly rebuilt but has been run at least a little bit before I bought it. Looking in the sump it is very clean and the cam looks like new, under the valve covers look pretty clean too but probably not a good indicator. Since I do not know when it was rebuilt maybe I should go with conventional oil one more change before switching to synthetic. The car will not see any real cold weather so not worried about that piece of it.

As mentioned above, the only leak it has seems to be coming from the oil canister. It does not seem to have much blow by and runs strong/no smoke.

It has vented valve covers and I vented the oil filler can to the Rt air cleaner as shown in pic (I know it is not the prettiest engine, but it is temporary while I rebuild the original):

[David Jones]

Mark, be careful on the oil canister seals. There are a variety of cans and the top bolt copper seal varies. The cap seal supplied with the new filter can be rubber or fiber. Some filters will not take the fiber one but I have never had an issue with the rubber ones. Also make sure you get that seal out. I have more than a few times found a second seal mashed in to the cap.