| [GMCnet] Dip stick calibration question [message #271499] |
Mon, 09 February 2015 10:41 |
glwgmc
Messages: 1014
Registered: June 2004
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I think it is time to wrap up this very interesting discussion. My thanks to all who contributed.
The ambiguity comes from the factory manuals of the 70’s as they relate to Olds 455 Toronado pans.
Both the motorhome manual (page 6A-65) and the Toro car manual (5-113) say to add 6 quarts at a change with a new filter and 5 quarts without a filter change. All of the sources I could find say the 455 Toro pan (GM part number 398438) holds 1Q more than the non-Toro 455 car pan and requires the use of a special dip stick and tube. The high performance sources say to not use the Toro pan on a street car running at high RPMs to gain the benefits of one more quart because the oil will be too close to the crank throws and it is improperly baffled for high RPM use.
KenH’s pics show 4.5” from the flange down is the correct full level for the oil to keep the throws from hitting the oil pool while going down the road. At that point there is a measured 3Q of oil in the sump. Try as we might, we are not able to explain why one can drain five quarts without a filter or six quarts including the filter if only 3 are in the sump and one is likely trapped in the shallow end of the pan.
Since the factory manuals for both the Toro car and the MH are consistent in saying drain and add 6 with a filter change, they either were wrong or had to expect the rest of that oil to be coming from drain down somewhere in the system. They also had to expect the oil above this level in the sump would be quickly pumped up into and kept elsewhere in the engine while going down the road at the low RPMs our coach engines see in normal service.
KenB’s, JimH’s and others experience with a bone stock MH 455 says not that much will come out at a change, so if you put that much back the engine will be over filled while running down the road and will read over filled on the dip stick at rest. MattC’s experience is somewhat similar from dyno experience from that time. We also hear reports from MH owners find that following the factory recommended add back may result in one quart being consumed quickly.
So, while not conclusive evidence (to me at least) that the factory was wrong, our conventional wisdom seems to stand that drain, change filter, add back 5Q, run and rest the engine to allow internal drain down will result in the proper dip stick full mark calibration regardless of external coolers, larger filters, etc.
AdrianG’s logic says the oil can be at the 3.5” mark (4 Q in the sump) going down the road without foaming the oil. If correct, that would bring us closer to the factory refill specifications of 6 quarts with filter at an oil change. MattC has offered two different methods for checking that, but each can be a bit cumbersome to implement and still leave room for measurement error.
Bottom line for me is to keep the full marks where they are for now and add 5.5 quarts with filter on the next oil change and see if that does result in being one half quart over the full mark and whether the half quart really does burn off quickly. Thanks again for all your contributions.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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