# how much oil?



## yousaygo (Apr 3, 2006)

Hi, 1969 GTO, i purchased last year, drivetrain was not installed, friend and i spent winter putting all the pieces together. The engine is a 1965 Pontiac 421, race built, Ross pistons, Eagle rods, Crower Beast Cam, i have all the paper work, dyno specs, etc...has not ever run in car, it is brand new/rebuilt, built in 1998 according to docs. Engine was packaged very nicely in a crate. The inside of the engine is in pristine condition, very professional work.

My question is, how do i know how much oil to put in? My reason is that it has a very large aluminum oil pan, i am guessing it is 7qt, it could be 8, not sure how to tell the difference. Will be using 20/50 w/zinc Valvoline race oil. 

Sorry for such a seemingly simple question, but i do not want to make any mistakes. We primed the motor correctly with primer tool. 
What makes it difficult also is the dip stick is not correct, i am not sure where the original is, the tube has an extension that brings the tube up to valve cover height. Once i know how much oil, i can mark the dip stick, my thinking goes.
Thank you sooo much in advance, truly awesome help everytime i post.
Sincerely, Shane


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## dimitri (Feb 13, 2009)

I really think that 20/W50 is way to thick. Most applications should run 10W30.

Oil is the blood of that engine. I would not attempt to start the car with the wrong dip stick. Make it right. It sounds like there is a lot of dinero put into that engine. If it were me I would make the dipstick correct.


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## geeteeohguy (Feb 2, 2008)

X2 with dimitri. Use an appropriate oil and verify the level. I'd use 10/30 or 15/40 at the most. It is probably 6 quarts with filter...my '65 389 is, and the pans are the same.


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## 68greengoat (Sep 15, 2005)

I read "very large aluminum oil pan" as an aftermarket. Maybe OP could be more specific. Didn't they vary in capacity?


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## geeteeohguy (Feb 2, 2008)

Missed that entirely. With an aftermarket pan, all bets are off. The best bet would be to somehow find the "fill line" in a stock engine and emulate it in this one. I wonder if there is a factory diagram showing fow far below the skirt of the block the oil level is??


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## yousaygo (Apr 3, 2006)

Hi, Yes the pan is surely aftermarket, it goes way below engine. I think finding the "fill line" is right on track.
My thinking was that an aftermarket pan would either be 7 or 8 quart, only those two choices. Wonder if there was some dimension that could confirm the capacity? I'll mess things up if i guess . Could i measure dimensions and do math for volume?

Also, that weight oil was recommended due to the cam and internal components.

THANKS...Shane


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## BearGFR (Aug 25, 2008)

yousaygo said:


> My question is, how do i know how much oil to put in? My reason is that it has a very large aluminum oil pan, i am guessing it is 7qt, it could be 8, not sure how to tell the difference. Will be using 20/50 w/zinc Valvoline race oil.


One thing first, that was pointed out a few days ago and was news to me at the time... is that race oil might not be a good idea. The reason is that although it does tend to have more "lubricity", it's not intended to stay in an engine for long periods of time and doesn't have the additives needed for that. It will tend to break down very quickly and will need to be changed much more often than a "normal" oil.

Now, on to the capacity question. You need to make sure that you accomplish a few things: 1) make sure there's enough oil in the system so that even with the motor running, under load, and with the car moving around and sloshing the oil (like in corners, hard acceleration and stuff) that the oil pump pickup stays completely covered in oil 100% of the time 2) that there's enough oil "volume" in the system so that the oil in the pan has enough time to cool and transfer some of the heat into the metal pan before getting pumped back into the motor (oil is also a major playing in cooling an engine) and 3) that there's not "so much" oil in the system that it gets whipped into foam by the spinning crankshaft. As long as you meet all of those goals, the actual volume of oil isn't all THAT critical. 

So, here's one way you might come up with an approximate "fill line" on your dip-stick. Take a piece of string and run it along side the outside of your dipstick tube, following the shape of the tube. Put marks on the string at the top of the tube and at the parting line between the block and the pan. What you're doing here is measuring the actual length of the tube. Take that same length of string and place it next to your dipstick with one of the marks at the top, where it sits on top of the dipstick tube. Make a third mark on the string at the bottom, where the end of the dipstick goes to. Now you can user that string, lining the top mark up with the top of the tube, and running it back down the outside of the tube (again following the contour of the tube) and make a pencil mark on the side of the pan that corresponds to the end of the dipstick. That'll show you how far down into the pan it reaches when it's inserted. You've got a 421, so that's a 4.00" stroke - so it's 2" from the block/pan parting line to the center of the rod journal when it's at it's lowest point. Add 1/2 of the rod journal size (1.125) to that plus "some" for the rod cap, bolts, counterweights, and "some room" --- call it another 1.5 inches, and you've got an approximation for the oil fill level at 4.625 (4 5/8) inches below the block/pan separation line. Put another pencil mark on the side of the pan there. If that turns out to be "deeper" than the "shallow part" of the pan below where the dipstick goes in, then put a mark about 1/4" "up" from the bottom of the pan at that point instead. The difference between that mark and the "end of the dipstick" mark will give you a decent approximation of where on the dipstick would be "full". It won't be perfect, but it should be "safe enough" for keeping the pan "full enough" without letting the oil get "into the crank" - at least until you can get some details on exactly what pan you have.

Bear


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