- I'm going to change the oil in my Catalina tomorrow, I had a hard time figuring out what the recommended oil weight was. I'm used to an engine requiring a specific weight of oil regardless of environmental temps. I found in my Catalina's owners manual that it has a range of oil weights, with 10W-30 being the broadest use. 5W-20 was not recommended for long drives above 55 MPH. Why did they design engines that way back in the day, and not with specific weights, like today?
I noticed the owner's manual says my 4.9L V8 only needs 4 quarts of oil, which is less than half of the 10 quarts a modern Ford Coyote V8 needs. Do modern VVT and dual overhead cam systems add that much extra oil demand? Even my '99 Ranger's 3.0 Vulcan V6 takes 1 quart more oil than this old V8, and it's also a basic pushrod engine, only with fuel injection, and no VVT.
Engines back then were not built to the same tolerances and did not have advanced features such as variable valve timing with complex hydraulics that require specific oil weights. Although synthetic oil was available it was not widely used. On old-school inline sixes and V8s typically the manufacturer would specify 10W30 or 10W40 oil be used under most conditions. (Lighter or heavier oil might be recommended for extreme temperatures.) When engines started to wear and use oil it was common to switch to 20W50 oil as long as temperatures didn't get much below freezing.
Also typically the engine would take 5 quarts of oil including what's in the filter, so the engine itself actually holds about 4 quarts. I always fill the new oil filter with fresh oil when doing a change, though some may drip out on installation depending on how it's positioned on the engine.
The lack of ZDDP in modern oils may be a concern in flat tappet engines, there are a lot of opinions out there. The general consensus seems to be that in a stock, non-performance engine that's broken in and not in heavy-duty service (pulling heavy trailers, etc.) it's not too much of a concern. You could add a ZDDP additive or use a high-ZDDP content specialty oil if desired. (I've had no issues using today's oils in my own flat-tappet engines.)
On that car I would just use a modern semi-synthetic oil of 10W30 or 10W40 weight and call it a day.
I bought an OEM AC-Delco filter and 5 quarts of Pennzoil's High Mileage conventional. I contemplated Platinum High Mileage, but considering the age and the fact I know next to nothing about this engine's history made me hesitate. I'd rather not have that full synthetic clean out all of the engine sludge at once and have oil leaks everywhere, haha. Would you put the whole 5 quart jug in there and call it a day, from what you described about the filter? The filter will hold at least a cup or so of oil.
That oil should be perfectly fine. (I mentioned semi-synthetic because in some areas it's been reported conventional oil is getting harder to find.)
What I would do is put 4 quarts of oil in the engine and fill the oil filter before spinning it on. Then start the engine and let it idle for a while, then turn off and check the oil. Top up as needed to reach the "full" mark on the dipstick. You don't want to overfill the crankcase and blow seals out.
Good questions. 👍 👍
