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Author Topic:   c-4 transmission fluid

Posts: 138
From: San Lorenzo, CA, USA
Registered: Aug 2001

posted 08-31-2001 05:14 PM     Click Here to See the Profile for rockafellz   Click Here to Email rockafellz     Edit/Delete Message   Reply w/Quote
Hey Everyone,

What kind of transmission fluid should I use on a stock c-4 (never rebuilt)?

Also, when I bought my car a few weeks ago I was looking through the receipts and found that when the last oil change was performed they used 20w50 oil... The engine had 97,000 miles on it and it has never been rebuilt. I think this is a little thick for a 289 block even if it hasnt' been rebuilt. I noticed that the oil pressure gauge stays in between fully low and 1/4. Does that seem right?

I plan to change the oil this weekend and I'm planning on going back to 10w30. What do you guys think? Stay with 20w50 or go back to 10w30? I'm figuring oil pressure is low due to the lack of oil being pumped? Am I wrong or almost right?

Please post your comments regarding what I should do. As always they are greatly appreciated.

Thanks in advance.


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Posts: 23085
From: Saco, Maine USA
Registered: May 99

posted 08-31-2001 06:42 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
20W50 is very thick. You oil pressure should go down when you switch to a 10W30 or 10W40, depending on how diluted the current oil is.

You should use a good quality mechanical oil pressure guage and get an accurate reading.

Use Type F only in your C4.

'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip
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Keep your driveway ALL Ford!!!

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Posts: 147
From: Ardmore, Ok. USA
Registered: Jul 99

posted 08-31-2001 06:44 PM     Click Here to See the Profile for PONYMAN   Click Here to Email PONYMAN     Edit/Delete Message   Reply w/Quote
I think it is more likely that your low oil pressure is due to a bad guage or sending unit, or bearing wear in the engine. I would obtain an aftermarket oil pressure guage and hook it up directly on the engine. This is a better way of telling the true engine oil pressure rather than relying on a 30 year old guage. As to type and weight of oil. Everyone has their preferences. I personally use 20W-50W Castrol in my 72 Mach 1 with a 351C. With the hot temperatures here in Oklahoma, I feel it gives me a little better protection. I personally would not change weights or brands of oil on a 97,000 mile engine. Might break loose some deposits. Better to wait until you have the engine rebuilt. On the C-4, I have a friend who has a transmission shop. He tells me that you can use either type F, or Dexron-Mercon in the older Ford transmissions. The type F will give you harder quicker shifts. The Dexron-Mercon will shift smoother, but not as quickly. Hope this helps. It is really not the type and brand of oil that is important, but the regular changing of both the oil and filter. Rick

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Posts: 15
From: Hermiston, OR, US
Registered: Jun 2001

posted 09-02-2001 11:54 PM     Click Here to See the Profile for macx   Click Here to Email macx     Edit/Delete Message   Reply w/Quote
DEFINITELY try a good reliable mechanical pressure gauge first! I've seen older hi miles motors use 20W50 when things are worn to the point of insufficient oil pressure on i.e. 10W30. Although more $, a full synthetic like mobil 1 has both much better lubricating ability as well as heat-breakdown resistance, AND you can get it in 15W40 or 20W50 (forget which) and yet flows fine so isn't too thick when cold at startup.

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Posts: 15
From: Hermiston, OR, US
Registered: Jun 2001

posted 09-02-2001 11:56 PM     Click Here to See the Profile for macx   Click Here to Email macx     Edit/Delete Message   Reply w/Quote
PS - on, in their tech articles, a gen Ford auto trans engineer says to use type F in any Ford non-od auto trans. for the best durabiloity and shifting, but you can also use Mercon as mentioned above. Type F prob best everything considered. (unless you can spring for a synthetic, which has higher heat resistance and more additives)

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Posts: 4135
From: So. Fl.
Registered: Aug 2000

posted 09-03-2001 08:39 AM     Click Here to See the Profile for mellowyellow     Edit/Delete Message   Reply w/Quote
Whether my trans rebuilder was giving me BS{ and I wondered} he said that the multi purpose was good owing to the different composition of replacement parts. So I am using the multi purpose, but would have preferred the type F. This has been discussed before and Alex strongly recommended type F.

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Posts: 279
From: Memphis, TN
Registered: Feb 2000

posted 09-04-2001 12:37 AM     Click Here to See the Profile for 65hoss   Click Here to Email 65hoss     Edit/Delete Message   Reply w/Quote
Yep, wait until Alex see this. F type only!!!

As far as oil for a street car, every mechanic I know suggest a straight 30 weight.

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