Ford 302 engine oil dipstick - 1995 OMC Cobra, Ford 302, VolvoSX

Recently realised I've been reading my dipstick wrong. It has a hashed area with top-up and full marks but well above the hashed area there are 2 stamped indents / pips.

The book says the engine takes 6 quarts of oil. If I put 6 quarts in it the dipstick reads well above the hashed area and the oil level comes to the lower stamped indent. If I only put 3 quarts in it the level might come to the top of the hashed area but then the engine would only have half the oil in it that it's supposed to have.

This isn't because the pan is full of stuff or becauses I didn't pump all the oil out, I rebuilt the engine so I know it was empty before I put any oil in. After building the engine I thought I'd put 6 quarts in, checked the level and it read overfilled according to the hashed area, pumped all the oil out, refilled with 4 quarts and it was still above the hashed area but 4 quarts was the least amount of oil I dare run the engine with, so I made my own mark on the stick at 4 quarts.

Why would the dipstick be like this? Is it because it was near the end of the model line and they were scraping the parts bin?

It may just be a dipstick that does not belong to this engine , but one from a different engine that was put in there, or the outer housing is shorter than it is supposed to be, which will cause the stick to go deeper inside the oilpan
If the book tells you to put in six quarts, than that is what is should be.
Just check online what the dipstick is supposed to look like and compare to what you have.

Put in the required amount if oil then mark your dipstick accordingly. Never know which, what kind of dipstick you have, so use the correct amount of oil and mark the dipstick accordingly !!

Thanks for the replies.

I'll come back to this thread and post a pic of the dipstick.

I don't think I'm the first to encounter this, I watched a Michael Romer YouTube vid in which he changes the engine oil on a Ford engine'd OMC Cobra setup, in the comments section someone else said they put in the supposed correct amount of oil and it read well over the dipstick full mark. Someone replied to that and said it must be because he hadn't pumped all the oil out or his oilpan must be full of crud, but that definitely isn't the case with mine. It could be the wrong dipstick but the stamp marks above the hashed area don't look like they were done by a previous owner.

I've been going through the exact same thing on my '95 302. I don't recall the dimples/indents you're referencing. Will check that. You'll be able to confirm you have the right dip stick since the part number is on it. I've just been putting in a quart less that listed, and it's been running well above the hash mark with no issues for several years.

Thanks, yes I'll check the part number when I get around to taking and posting a pic of the dipstick. The pic will show what I mean re the hashed area and dimples.

One thing that got me second guessing was the oil pan looked in great condition and I knew the engine had been rebuilt before.. I thought it possible someone could have swapped in a smaller capacity oil pan during the previous rebuild, in which case if I filled with the amount of oil the manual said it could've caused problems with oil foaming due to being overfilled. So I went with the smallest amount of oil I dare run it with which was still above the hatched area on the stick.

Slightly different subject - What oil do you run in your '95 302 @Horigan? My manual says old-skool straight 30 oil, I'm second guessing that too lol. If the engine was in a car/truck on this year Ford would recommend something like 5/30 synthetic. On the one hand I think OMC might've been slow to change their advice so stuck to recommending 30 grade when a multigrade (maybe synthetic) might be better. On the other hand our (or at least my) 302 has a hydraulic flat tappet cam when on the same year a road vehicle would have a hydraulic roller cam... But I'm not sure if a modern straight 30 grade would have any more zinc to protect the cam than a modern multigrade or synthetic. There's also the general advice about not switching to synthetic (with more detergents than mineral) if mineral has been used for a long time because the detergents could dislodge crud... but I only rebuilt my engine last year and now it's thoroughly run in I'd like to prevent crud build up by using an oil with more detergents. I used 20/50 mineral oil to run it in, changed that several times last year then put straight 30 in it during winterising, ran it with that straight 30 most of this year but switched back to the 20/50 because I thought it'd help keep oil pressure higher when returning to idle after an extended run on the plane. I've found oil pressure does stay a bit higher with the 20/50, especially now I've put a greater quantity of oil in it. Since I don't believe the straight 30 or 20/50 mineral oil has any more zinc than synthetic I was going to switch to synthetic of something like 15/40 or 20/40 but used the 20/50 mineral when I couldn't get hold of any synthetic around those grades locally.

The type of engine oil is a bit tricky. Marine engine oil is a different type (the additives) because these engines run long periods of time at the same rpm.
Around here the 15-40 ,although it is usually advertised for diesel engines, is quite popular. That is because it is made for engines that run at the same rpm for longer times. 30 or 5-30 are good for gasoline engines that run variable rpm or run for short times. The 5-30 is a cold weather oil.

Even if the dipstick has the correct part number, doesn't mean it wasn't a bad stamping when it was made. Are there different size oil pans made for that engine. I would not be a fan if running on low oil just to make the dipstick look more accurate.

Dipstick pic showing the 'safe' area and the 2 dimples. The oil is up to (down to in the pic but you know what I mean) halfway between the dimples, which is way above the 'safe' area. It's way above the safe area if I only put 4 quarts/litres in but it's between the dimples with 6 litres in. You can see the lowest dimple on the stick is right beside the M after the part number. I previously referred to hatched area, it's not hatched it just has the words 'add' and 'safe' between a couple of lines but for intents and purposes it's the same as a hatched area.



Made a few changes to the wiring. Power to the ignition coil is now switched through a relay, the ignition on position just energises the relay. The other red wires and fuse holders are because I wired some extra accessory sockets to the engine instead of to one of the 2 batteries so when I use the battery switch it affects where the accessory sockets get power from too.



This dipstick pic might show the indents / pips a bit better.



I have yet to check if the dipstick part number 3850474 is supposedly correct for this engine.

Does your stick have the pips @Horigan?

I'm wondering since OMC/Volvo used both GM and Ford engines, if they used the same dipstick and different markings on both, you could figure that out by checking part #s. I have a similar system on my '88 4.3, but it just has the hash marks no dimples that I've noticed but next time I'm at the boat I'll check.
One idiosyncrasy with this system that I've noted is that it gives inaccurate readings depending on how you check the oil. The trick is to pull the stick out and wait a few minutes for the oil level in the tube to equalize. Then it reads correctly, this holds for both checking it cold before running and hot after running. Example, when cold, I think the air in the tube contracts and pulls the level of oil up the stick looking like it's way overfull. But if you pull out the stick and wait a few min, then re-check, it reads correctly. Right after running the opposite happens, it reads low, presumably because hot air in the tube prevents the oil from finding it's level in the tube. Then if you do the same thing, pull the stick and wait a few min and recheck, it reads correctly.
Lastly, oil choice. I think that straight weights were recommended when syn oil wasn't so common because the Viscosity Index improvers that are used in conventional multi vis oils could break down with high rpm use and cause problems with low viscosity oil and also the VI improvers were known to cause piston ring sticking. Straight weight oils even dino do not need or use VI improvers. Since syn oils can be blended to be a multi vis without VI improvers (or so I've read) it is less of an issue with them. I have used straight 30, Merc 25/40 conventional and Merc 25/50 syn blend, the 2 Merc oils held their viscosity the best in oil analyses I have done over the years. They are expensive but I feel meet the need of marine engine operational conditions.

airshot said:

Even if the dipstick has the correct part number, doesn't mean it wasn't a bad stamping when it was made. Are there different size oil pans made for that engine. I would not be a fan if running on low oil just to make the dipstick look more accurate.

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I still haven't totally confirmed it's the correct dipstick for this engine but a quick Google of the part number shows it is an OMC Cobra stick. I hadn't posted pics of the stick when you posted but I don't think it looks like a bad stamping, though it would be easy for a DIYer to stamp the pips.

Agreed it would be daft to modify the dipstick to make it read like level is OK when it's not, that much seems common sense. The reason I marked the stick at 4L/quarts was because I knew that was how much I'd put in it but the stick read well above the safe area, 4L was the minimum I dared put in it. I measured the length of the stick against the length of the tube to try to get a sense of how high in the pan the oil would be but it occurred to me that still wouldn't tell me if the crank was whipping up the oil.

Don't think I know of a factory pan for any model car/truck/boat that would make the correct amount of oil for the engine (and for this stick to read in the safe area) when the engine is filled with only around 3 litres/quarts. The pan looks factory, I might be able to dig out pics I took of the engine on an engine stand with the pan fitted, others might be able to say whether the pan looks standard. Since realising about the pips I think the pan is standard for the boat and that it should take 6 quarts, just the stick has the 'safe' etc markings on it when the pips are really the correct level.

Dipstick 3850474 is the dipstick that is used with the engine oil extraction suction tube. The tube that it goes through has all sorts of bends and turns. If your engine just has the straight down housing 3850249, but the 3850474 dipstick it will go much deeper into the oil pan and it may even touch the bottom.

rolmops said:

Dipstick 3850474 is the dipstick that is used with the engine oil extraction suction tube. The tube that it goes through has all sorts of bends and turns. If your engine just has the straight down housing 3850249, but the 3850474 dipstick it will go much deeper into the oil pan and it may even touch the bottom.

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My engine does have the oil extraction / dipstick tube. It goes down the port side of the engine, completely around the back of / under the oil pan and enters the sump through what would be the drain plug hole on the starboard side of the pan. I posted a picture of the engine above.

So it seems according to the numbers you mentioned I have the correct model number dipstick for this engine?

based on the part number here it looks like you have the right dip stick, but don't know why it has both the dimples and hash marks
I'd start with the oil drained, fill the listed quantity and if the dimples are in line with it being full, use them ignore the hash marks.

Lou C said:

https://www.marineengine.com/parts/omc-parts/omc-boat-parts.php?year=1995&hp=5.0&model=502APHUB&manufacturer=OMC+stern+drive&section=Oil+Pan+%26amp%3B+Oil+Pump

based on the part number here it looks like you have the right dip stick, but don't know why it has both the dimples and hash marks
I'd start with the oil drained, fill the listed quantity and if the dimples are in line with it being full, use them ignore the hash marks.

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Thanks Lou.

That's effectively what I've done.

I was using the term hash marks but it's got 'add' and 'safe' lines (not hash marks) in addition to the dimples.

Is my dipstick different to other 3850474 dipsticks? Do they usually have the add and safe areas / in the same position as mine? Do they usually have the dimples?

Hard to say I wonder if you could put out this question to forum members that have OMC/Volvo Ford engines in that age range. If you look at that catalog link I posted you can check to see how many model years that part number was used on the Ford 5.0 V8.

rolmops said:

...or the outer housing is shorter than it is supposed to be, which will cause the stick to go deeper inside the oilpan

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It has just occurred to me that when I was rebuilding the engine I wasn't sure whether the outer housing / tube was supposed to be fitted so it runs down the port side of the engine then bends to run under the pan before bending again to connect to the starboard side of the pan, or supposed to be fitted so it runs down the port side of the engine then bends to run around the back of the pan before bending again to connect to the starboard side of the engine. I don't remember how I routed the tube but I suppose it could be fitted to run at different angles around the pan and the angles could make a difference to the effective length of the tube. But I could see where the clamp that connects to an exhaust bolt had been around the tube and refitted it so the clamp is in the same position on the tube, so I believe the top of the tube is at the correct height and the stick measures height of oil in the tube not directly in the pan.

It looks like the 5.0 & 5.8 Fords were used by OMC from 1989 to 1996. Not sure if Volvo did the same….

That’s the same dipstick part number for my 302, though I don’t have the dimples. I believe my oil tube goes to the port side of the oil pan.

For oil I use Rotella T4 15w-40.