Let's Talk Engine Oil...

[Guest imouttahere]

I was curious about what viscosity of oil other Dodge Brothers are using in their 4-cylinder cars.

I'm using detergent oil, and am convinced it is preferable to non-detergent, so you're not going to change my mind on that issue.

My DB has a rebuilt engine that runs well, uses no oil and has no unusual noises, and I want to keep it that way if possible.

In most of my cars (all older models, 1960 and newer) I use 20/50 weight detergent oil, and I have been happy with it in those cars. I wouldn't want to use 20/50 in my DB, however, because I think it is a little too thin for the DB's bearing clearances.

Until now, I've been using straight 30 weight detergent in the DB, but I'm wondering if maybe I should be using 40 weight detergent.

Whatsay, Dodge Brethren?

[FMF]

My '25 has 43,000 original miles -- engine never rebuilt.

I use 40W non-detergent and change it once a year in July.

I drive it approx. 250 - 300 miles/year.

[Guest imported_woodwheels]

You have used the most important word to describe the condition of your engine, for oil type, rebuilt as has FMF, original. Modern detergent oils are vastly superior, in every way, to non detergent, single viscosity oils. A 43000 mile original engine, however, will be ruined by using a detergent oil. The detergents break loose the long built up residues from every nook and cranney, pump them into the journals and throughout the engine causing a major mechanical failure. This process usually takes several thousand miles to make itself apparent. Under no circumstances should an engine that has been run on nondetergent oil have detergent oil introduced.

Any engine that is cleaned out via the process of a professional engine rebuild will benefit from the use of a modern detergent oil. Those of us, like FMF, with antiques that change the oil very frequently are investing in a form of insurance that has a proven return. Changing the oil before one stores the car for the winter insures that the engine rests in a clean bed not one that eats at the parts and pieces while the machine is in fallow. Acids in suspension are terrible thing.

Multi viscosity oils are truely the best thing one can invest in for the old high torque low RPM designs. For most of us our antiques are driven at a faster pace than the roads of the 20's and 30's allowed. Changing viscosity when the heat increases is absolutely the best thing for the health of the machine. Engines, transmissions and rear ends all benefit from this technology. Flushing the rear axle and trans is a cheap way of adding years to their life and in most situations improving their performance. 2 oil changes with about 200 miles in between is worth the expense. 80-140 is worth considering when 100 and 160 were recommended for winter and summer.

Modern oils retain their viscosity better without the need to be as thick as molasis. They penetrate and remove heat at a pace that was impossible just 20 years ago. The 20-50 question is a good one. Most of us do not put 10,000 miles a year on our antiques. I vote for the best possible protection and what ever it takes for sustained OEM oil pressure. I also use 20-50 for that reason. Does 50w mean my engine will need a rebuild at 80,000 instead of 95,000 because of ring wear? Probably, but at 1000 miles a year I do not think it is an issue.

Jim

[Guest oldodgeboys]

My understanding is that petroleum oil oxidizes from moisture in the air. Oil should be changed more often. Any experts out there on this?

Anyone have thoughts on synthetic oil?

[gundog99]

Is your car fitted with an oil filter? As I understand it multi grade detergent oil holds the residues in suspension, until they are removed by filtration ;with non detergent oil, the residues mainly fall to the bottom of the sump as the oil passes through. One other factor you need to consider is weather or not the oil is compatible with the cars bronze and white metal bearings.

[Guest imported_woodwheels]

FMF has a 43,000 mile original engine. Yes,non det oil leaves most of its particles in the sump. The other nooks and crannies are the problem. If you have an untouched engine like FMF's you can remove most of the crud by dropping the pan, cleaning it and the oil screen and reassembling.

All filters untill Ford introduced the spin on filter in the late 50"s, were by pass systems. With these old style filters the oil was recirculated many times before the entire volumn was run through the filter. The spin on full flow washed 100% of the oil each cicrulation cycle. Crud is built up on the under side of piston rings all through the valve train and on both sides of all bearing caps and receiver ends. Anywhere there is movement and heat is suspect for some debris to hide. Introduced det oil to a non det system breaks loose this junk and pumps it to the machined surfaces. The machined surfaces fail after the break loose process sets in, with heat/friction being applied.

How long it takes the destruction process to mature depends on how the engine is driven. If the machine is driven short distances at low speed then it could take years. If the engine is switched over and driven 1500 miles in 3 days the proces would most likely prevail in less than a week. The time would be extended considerably if the clean out of the oil pan and screen was done first.

As time marches on fewer and fewer HPOF engines survive. They simply do not run as well as they should because of metal fatigue at spots like the piston rings and valve springs. During the 60's - mid 80's no qualified antique dealer would risk an engine change over without being absolutely sure of its oil history.

I stand by applying det oil to any rebuilt insert bearing engine. Make sure your viscosity is correct. Only engines that are 100% irrigation should be run without a pressure gauge but should have an oil temp gauge. An old argument is that slung bearings need non det oil because the crud build up is good for the system. Someone else needs to weigh in with slung bearing facts and knowledge.

Someone with a chemistry background needs to answer old dodge boys question except for the idea that oil changed more often is far better and cheaper than oil not changed enough. Always drain oil hot and never let an engine sit for a winter with dirty oil in it.

Jim