Topic: Oil for 51 CM


Tracker    -- 01-21-2016 @ 10:34 AM
  For all the great advice & help I have received from this forum, I like to report back on things that work & do not work on this priceless old cars.

Less than 1,000 miles ago ,I did an oil-filter change using Rotella 20-50 conventional oil..I even used a hand pump to pull every ounce of the oil from the filter canister.After all the set backs I had with my car recently, I decided to finish up success with a new oil change. I was amazed to see how black the Rotella oil was...it was almost like sludge. But in less than 1,000 miles ? does not make sense to me.

I am now using Castrol 20-50 Conventional oil with a new Wix filer. Has anyone else had a similar experience ?

Tracker


TomO    -- 01-22-2016 @ 6:50 AM
  The condition that you describe, can be attributed to not getting the oil warm enough to evaporate all of the moisture and unburned gas in the oil.

Your engine problems kept you from driving the car enough (at least 30 minutes) to get the oil hot, also you probably had a lot of idling time while you were trying to resolve your problem.

Your spark plugs are probably showing signs of excessive idling also. They will get a buildup of carbon, when this occurs.

This will happen with any brand of oil.

I like to use 10w-30 in my cars.

Tom

This message was edited by TomO on 1-22-16 @ 6:51 AM


Tracker    -- 01-22-2016 @ 3:17 PM
  Thanks Tom .....as always you have the answers. The oil
was the blackest I have ever seen motor oil at any time in any car I have ever dealt with. It stunk to high heaven although not a gasoline smell. I had never used Rotella prior to these events so I was wondering about my choice of oil for this age engine.

The plugs were as you say, heavily carboned up so I installed a new set of Autolites. The distributor was the real key to success. I installed a new Airtex in line pump which seems to be a lot more efficient but the mechanical carry's the load and I have yet to use the electrical which is my backup.

Again, thanks for your response Tom.

Tracker



Superdave    -- 02-20-2016 @ 12:43 PM
  This is for freshly rebuilt engines..
Something to keep in mind. Presently the way machine shops clean old engine blocks is to put them in a very hot oven. EPA just about makes solvent cleaning obsolete. That "baking" process created a lot of black ash...inside the oil passages! if not thoroughly mechanically cleaned out. Like with long brushes the oil will pick it up and circulate it. I have had to clean every block I have had done from several different shops . Amazing how much cr*p I have found..even in crank shafts that are drilled.



56MarkII    -- 06-15-2016 @ 10:56 AM
  I've owned my 50 for 35 plus years now and for most of the time 95% all I ever used was a good brand of regular 5w30 with NO problems. I rebuilt my engine 34 years ago and used this since. Once I used 15w40 and when my Merc. sat for a while I had valves sticking. Out it went and back in went 5w30. Once I used mobile Synthetic and my crankshaft seals stayed dry even though they are a bit tired after all these years. I've heard old wives tales about older engines leaking like sieves because the gaskets were not designed for synthetic. Total BS! The only problem I had with the synthetic was when my Merc. sat in storage for over a year the valves stuck bad enough to cause the engine to miss on a number of cylinders until they finally freed themselves up. This included a slight trickle of diesel down the carburetor while the engine was on fast idle. I was told and read a while later that the problem with synthetic is it tends to totally run down back into the oil pan leaving things dry alot more than regular mineral oil. Must be some fact to that because I have no sticking valve problems with 5w30.
As for the type of oil that you use in a freshly rebuilt engine??
DO NOT USE A HEAVY EXPENSIVE OIL!!
I used to work at a John Deere dealership for over 8 years and John Deere has a so called break in oil. From what I was told by a service rep is it is a lighter regular 10w30 oil. Nothing fancy at all and this is what we always used in new or rebuilt engines. The lighter lower grade of oil helps the rings seat in better and in most gas engines including our flatheads, the pistons and rings only get lubricated by the oil thrown off or sprayed from the rods through a tiny hole in the side. of the connecting rod bearings and whatever oil is splashing around in the crankcase. The same thing applies to your camshaft and BTW did you ever see how your valves are lubricated? By oil mist that makes it's way through the drain holes in the lifter/valve valley under the intake manifold. There are small metal shields or deflectors snapped onto the steel oil lubrication pipe to limit the amount of oil sprayed up into this valley. I have rebuilt 5 of these engines (among many others) and everyone of these flatheads I have thrown these steel covers away to allow more oil up there with NO oil consumption problems. The lighter oil keeps the engine cleaner as well due to things getting washed with a spray of lighter oil.
My Merc. gets most of its miles on the highway mostly driving to car shows and meets and has stood up very well using a lighter oil. It is not pulling a boat and trailer nor is it on a race track and throughout the 70's all of your big Oldsmobile's had 5w30 as the recommended oil.

This message was edited by 56MarkII on 6-15-16 @ 10:58 AM


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