Why not share the engine and transmission sump?I imagine the oil engineers could make a compatible fluid,this will probaly become a mote point eventually as more electric drivetrains come into existence.-Kevin
Because engine oil is more quickly contaminated. Also they do different things.
That said, many motorcycles share oil between the engine and trans.
@kmccune: âWhy not share the engine and transmission sump?â
âŠbecause that would increase the amount of oil you have to change during each oil change. In my Civic, the engine holds about 4 quarts of oil, and the manual transmission holds about 2 quarts of oil. The four quarts of engine oil get changed about three times a year, while the two quarts of transmission oil get changed about once every three years.
Motorcycles share oil between engine and transmission because the oil capacity is already pretty low, so changing both doesnât have such a dramatic effect on overall usage.
They tried that in some of the early automatics. Because of the presence of combustion in the engine, engine oil needs changing much more often than transmission fluid.
The Model T planetary transmission shared the oil with the engine.
My Saturn SL2 has a transmission drain plug and a spin-on type filter for the transmission oil. It is actually easier to change the transmission fluid than the engine oil as the motor oil will always spill onto the cross-member when you remove the engine oil filter on this car. The placement of the transmission oil filter is perfect, the fluid drains perfectly into my pan below the drain plug.
@DannoDetroiyâ
May I presume that your transmission does not have a stamped steel pan?
I guess one advantage of no drain plug is that with no drain plug, the drain plug canât be accidentally left off and all the transmission fluid drains out and ruins the transmission to the tune of $2500.
I was reminded of this âoh, I forgotâ contingency by listening to Car Talk today. A lady was driving her older car from Texas to Boston or something like that, and Tom and Ray had a bet whether sheâd make it without needing major repairs along the way or not. It turned out she made it, but there was one incident. Before the trip someone â a friend of hers maybe â had added some oil to top-off the engine, and they forgot to put the oil cap back on the valve cover. As you might expect this created a problem. Fortunately the lady saw it before major engine damage was done, and stopped to buy a replacement oil cap.
But if there had been no oil cap, no one could have accidentally forgotten to put it back on. Iâm not saying cars shouldnât have oil caps, but the car engineers may go through that kind of thought process when deciding if it is worth it to put a transmission drain plug in. Itâs a compromise.
If an engine has no oil in it it will run and self destruct. If an automatic transmission has no oil in it it wonât do anything. All gears will be like neutral. No servos, clutches, bands will operate. Running it very briefly is not likely to damage anything since the few things that will be rotating will have a coating of oil on them and almost no stress without hydraulic pressure in the system. Boy am I gonna get creamed in this one. I know by previous posts that most will disagree.
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Yes, the Saturn S series do not have a pan that must be dropped to change the transmission oil. Saturn has a drain plug and a spin on type filter, just like changing your motor oil, simple and easy.
Way to go
A thread that was for 3-1/2 months is now back on life support
Not having a drain plug is not done to save money. Itâs an engineering preference. Some transmissions do very well on drain and refill, others may do better if the pan, filter and fluid are all cleaned and changed. A plug is just another thing to leak doing a maintenance in a way not recommended by the manufacturer. The same exists for the rear differential. Some have plugs, some donât depending on how they were manufactured. . A plug for some components would be compromises for what was intended as the correct maintenance procedure as intended in itâs design. Thatâs my story ! IMHO, a lot of easily maintained items are changed in design to both encourage you to go back to the dealer or engineer the life of all the components to near the same length of time. Cars are not designed to last forever and encouraging limited life by eliminating drain plugs is more of an engineering decision then it is to make it convenient for the mechanic.
@dagosaâ
Iâd still rather have a trans pan WITH drain plug
Itâs sometimes very difficult to lower a full hot pan without making a mess. Thereâs only so much you can drain out if you leave just one bolt in and lower one side. Thereâs still a considerable amount in the pan, just waiting to spill out
âItâs an engineering preference.â
In that case, the engineers are cheapskates and F . C . ING A . . H . LES
Hereâs my âproofâ . . . ALL of the 4L80E pans that Iâve seen have that âdentâ where the drain plug would be. Yet many of them donât have a drain plug. If the engineers didnât have those attributes I just mentioned, they would have specâd it out so that all of the pans have drain plugs
Lack of a drain plug on a stamped steel trans pan is penny pinching
Nothing more and nothing less
You can rationalize it all you want, but itâs still penny pinching
I donât deny that itâs more convenient for a mechanic but it does encourage drain and refill which may not be recommended. I completely disagree that penny pitching goes on to that extent in manufacturing. If they thought that putting in a drain plug would accomplish a goal, it would be done in a heart beat regardless of the cost.
An engineer at Lemforder, a subcontractor for Ford among others, told me they offered Ford a substitute engine part that was of greater quality ( In order to save the subcontractor retooling costs) for the same or LESS money. Ford adamantly refused and threatened to take their business elsewhere to get the lower quality parts. It better conformed to their design intent of their idea of itâs life expectancy.
According to the engineer, this is NOT uncommon. They do not do things just to save money during manufacture if it does not conform to other factors. This is the case of drain plugs. That there is dent there, indicates they wanted it drained in a particular way. I agree that full service could be better accomplished with a plugâŠno doubt. It would save time and money for the customer and mechanic and produce a longer lasting productâŠthat is not their intent. Maybe in years past, but everything is evaluated to the nth degree that drain plugs, IMHO, are included or not based upon by more factors then justâŠsaving a dime.
Where we disagree isâŠyou call it penny pinching, I call it long term penny âearningâ.
"An engineer at Lemforder, a subcontractor for Ford among others, told me they offered Ford a substitute engine part that was of greater quality ( In order to save the subcontractor retooling costs) for the same or LESS money. Ford adamantly refused and threatened to take their business elsewhere to get the lower quality parts."
I find this hard to believe, at least how itâs stated. Weâve seen in the case of the GM ignition switch how GM was more concerned with saving pennies on parts purchases than just about anything else, even if saving a few pennies per car ended up killing people.
If Ford refused a lower-cost higher-quality part, they must have had some other reason that was not evident to the Lemforder engineer. I have a hard time imagining it was because Ford wanted their cars to cost more and break down more frequently.
@jasmed1. You can believe what you want. But this is the more complete story. The part (a crank) was completely burnished which resulted in a part that was more easily cooled by oil during operation which increased itâs longevity and uniform flow through the rest of the motor. It was furnished to Nissan according to their spec. The part was a perfect substitute for the Ford part excluding the additional work. Making a substitute part for them required retooling which was a substantial increase in cost to them ( the sub contractor). According to the Engineer, Ford was readily aware that the part could be had for the same or a negotiated, less amount. This is not uncommon for subcontractors t o do to save money for themselves too,
Of course, if a switch already meets their intended design parameters, they are out to save every cent. That goes without saying. It just doesnât happen when it conflicts with their intent. Most people are under the illusion that car makers want to make cars that are as reliable as possible even if it does not cost them much if any more. Nothing could be farther from the truth. Automobile merchandising is much more complicated then that nearly as much is made on parts and service as on sales alone for car makers and dealers. You donât make a car that doesnât need service and expect to survive.
@dagosaâ
Here is your proof
GM produced both of those pans. In one case, they were clearly pinching pennies. Yet in both cases, the âdentâ to protect the drain plug is there. Whether they installed it at the factory or not
PENNY PINCHING . . . NOT PENNY EARNING
Iâm sorry, but I can not and will not see it your way
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I agree with db4690 and every car maker does it; every single one.
As I mentioned previously, itâs not just the cost of the drain plug itself which adds up over production runs of millions of cars.
Thereâs the added cost of machine tool wear (always $$$$) and the labor involved in the manufacture and installation of that plug.
A comparatively small cost all alone on one car; a huge cost when multiplied by millions.
Toyota no longer puts dip sticks in many of their transmissions. It has nothing to do with saving money on dipsticks. A well designed dipstick has to cost more then a drain plug to integrate into the engine compartment. It also has to do with their intent on HOW they want the transmission serviced and WHOM they want doing it. Drain plugs encourage do it âyourselfersâ to do that service themselves. Heck for years, I serviced manual and automatic transmissions with drain plugs myself and buying cars with drain and fill components as a reason for buying the vehicles I did. Rear diffs on Nissan and Toyota trucks are very popular with off road do it yourself fanatics who want components they can work themselves, they had drain plugs. That is changing ! For a couple of reasons. Do it yourselfers cost valuable profits for dealers and they make mistakes compromising reliability of cars as much as they help sometimes. Their components can also last longer without service frequency of old. These are the important factors, not just saving pennies for drin plugs. You know that better then I. That is the same merchandising decision along with engineering considerations on transmissions.
@db4690. ! These factors contribute much more to Toyotas coffers then the pennies saved by not having drain plugs for their own sake.
Btw my good friend. All I see is the absence of drain plugs, not the reasoning behind it. We are just debating intent, not outcomes.
Now, should the ICE last too much longer, we just might have oil dipsticks and drain plugs eliminated for oil changes too. Will you all say " thatâs just to save a few pennies by making the oil pan cheaper times the number of cars built." ??? Heck no ! And, neither is it the same case here !