VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 600W/SEA160 oil

I'm going to drain all my fluids in my '25 sedan. What is the best/correct oil to use. I see many types of 600W oil for sale. All different ISO numbers assigned to(Mobil) 600W oils. I've read that SEA 160 is the modern equivalent. Any guidance would be appreciated. Thanks;
Steve

I recently did this on my '26. I used Lubriplate SPO-299. It's formulated for early transmissions and rear axles.

You can learn more about it here: https://www.lubriplate.com/Online-Store/2-lb-bottles/SPO-299-one-quart-bottle.html

Thanks for your input Haase.

An SAE 250 grade of oil is way too thick,especially in a gearbox,but might be O.K. in a diff.Might be good if you live somewhere with a hot climate.An SAE 140/160 non-EP oil(straight mineral oil)would be a better choice,as that's approximately the equivalent of the original 600W. oil.Penrite make a transoil 140

I use Penrite 250 in the gearbox and diff. Says for vintage cars where 600w oil is recomended on bottle.

Steve from The Filling Station here. We sell 600W gear oil which is equal to the modern 160W. Here is a brief blurb from our website: "This gear oil is a 600W substitute modern equivalent with a designation of ISO 680. This is also an equivalent for SAE 160 gear oil. Our 600W gear oil is used in early transmissions, differentials, shackles & steering boxes from the 1920's & mid 1930's. Refer to your specific owners manual to determine if this oil is correct for your application. It is important to note that this gear oil has no additives (like modern oils) that will attack brass or bronze parts that are in the early transmissions and differentials." Our part number is VT-40 and it sells for $8.75 per quart.

Thanks Steve