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Discussion Starter #1 (Edited by Moderator)
I purchased a '94 Suburban c2500 6.5TD from an elderly neighbor ...lots of low grade deferred maintanence--but the first thing I did was change oil. It had a full size style AC/Delco oil filter (pre-pf1218). I replaced filter with a WIX filter (which is slightly smaller) and 7 quarts of oil (including filter)--as per 1994 engine specs. After letting it settle--it was low (as per dipstick)--ended up adding the remaining quart--which brought it right up to the line on the dipstick. Its been about 3 months and its getting quite cold here---so decided to change again (original oil was like mud--so an extra short change period couldn't hurt) to Mobil 5-30. Again--it took exactly 8 quarts.

So---everyone tells me that the 94 should take 7 quarts--and the 99 engine and up takes 8 quarts...and I guess either the dipstick is wrong---or maybe an engine swap was done?? neighbor is now in nursing home--and not available to ask. Or did a 94 ever have a larger oil capacity than usually listed. Its an "F" vin.

There are a few other clues--fuel return lines replaced with 3/8 Softline and fueline from lift pump up was also replaced with 3/8 line--ie..not hard line.

Any easy way to tell if engine was swapped out? or--if dipstick was replaced with a wrong one (is that possible) am I over filling.

Inquiring minds want to know...help!
 

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YOU NEED DIESEL RATED MOTOR OIL which is mostly 15w-40 or 5w-40.

There is no diesel rated 5w-30 oil from Mobil.

Diesel rated oil specification usually start with a Cx like CK or CJ.
The oil with SN or SM rating is only for gasser.
 
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Describe the dip stick handle or upload a photo.
Dip stick should have a part number on it.
 

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A question for some of the other experts here, since he has a C truck is it possible it has a different oil pan? From a van or an H1? Or like someone else was saying maybe the engine / dipstick tube is from another engine with the C truck pan. I actually don't know is the C and K truck the same pan?


The 5-30 oil also caught my eye too just because its not that commonly used for our trucks. It is the OEM oil for a lot of current diesels so you do find it on the shelves now in many stores. Mobil does make a 5w-30 version in the Delvac line so as long as that is what he has and isn't planning on working it hard especially when it warms up again he should be fine.
 

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Discussion Starter #6 (Edited by Moderator)
Thanks for all the good ideas...I will upload a photo of dipstick..and look for part number. BTW...I do use Delvac...which around these parts is common diesel winter oil. I am not working engine hard at this point..as I'm still kind of trying to put it in good working order.
 

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Discussion Starter #7 (Edited by Moderator)
Oh...and I misspoke ... it is 5w40 delvac...!
 
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Oh...and I misspoke ... it is 5w40 delvac...!
Phew, relief. Never ever use a Gasoline-only oil in a Diesel engine. There's some tolerance for Diesel oil in Gas engines but it's not the same the other way around.
 

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My 94 takes 8 quarts to get to the Full mark. I was always used to putting 7 quarts in my Dad's 6.2's over the years. I put 7 in the 94 the first oil change and when I checked it, it was low. Every oil change since, I put in 7, check it, and have to add the 8th quart. Not sure if the engine is original since the truck had almost 200K miles when I got it, but it appeared to be unmolested.
 
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Discussion Starter #10
Attached is photo of dipstick. Part number is 10244633.
 

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Discussion Starter #12
well...Looks like its got the right dipstick and dipstick tube, etc...

Guessing there must be some 94's that do in fact take 8 quarts...can't think of any other explanation....any thoughts, advice??
 

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Check the oil cooler lines?
They are prone to leaking where the rubber crimp to the metal tube.
 

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I have an upgraded filter on mine... its a bit larger. If you have a large filter, it will make the capacity go up.
 
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Discussion Starter #16 (Edited by Moderator)
still trying to figure it out...

Thanks for all the good suggestions. Here's where I am at--checked tab and fit of the dipstick tube--appears normal. no jamming, etc...

The oil lines are not leaking...supposedly done about a year ago--but I did doublecheck and there are no leaks anywhere. Keep in mind the oil level I checked was immediately after putting in the oil--so also no time for any mysterious consumption.

New oil filter is smaller than the older one--the new one I put on is a WIX XP--which appears to be a little shorter than the old ac/delco filter..

so....for now --I've decided to fill to dipstick level--ie--8 quarts. I'm pretty leary about running it a quart low (by dipstick). I appreciate all the help--you guys are all great to take the time to post on such a weird trivial issue. But--I surely don't want to overfill--and I don't have nearly the knowledge of this group.
 
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At the end, I don't think it will be detrimental at 8 Qts.
Now, if it needs 12 Qts, then it will be a different story because the pan is not that big.

I think it is well within the tolerance.
 
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^^^ plus 1.......when I checked some time ago...the oe part#s for the oil pan seemed common across most models from early year like yours to late (8 quart) models.

It seemed the only main change to accommodate the higher oil quantity was a change to the dipstick /tube..........Manufacturer advertising at the time said the increased level of oil was to provide better serviceability across service interval/less maintenance etc.
 
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I could run a PF25 or PF35 (I think those were the numbers) on my '82 6.2 2wd. One held a 1/2 at or more of oil than the other.
 
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