Which Break In Method For You?

[BIGLRY]

You're right Wiggy. Engines are built with such tight and precise tolerances that a lot of engines come with synthetic as a factory fill. Years ago manufacturers used to recommend 1000 miles before switching over. I changed my B over to Mobil 1 at 500 miles. Same on my 109.

Now I know I'm dating myself, but I remember when for a new engine the recommendation was to use a non-detergent oil till the first oil change then switch over to a detergent oil..... I suspect not may of the young whippersnappers today have ever heard of it. Like turn signals which became mandatory around the US in 1957 oil filters were an option on early cage engines. I have a 1954 five window Chev 1/4 ton truck I'm restoring with the first 235ci six with insert rod bearings and it did not come with an oil filter it was added by the dealer when my grandmother bought the truck new.

https://www.fillingstation.com/artic...yengineoil.htm

When early engines (prior to 1954) were new, oil filters were an accessory item and non-detergent oil was the type of oil used. Original, unrestored engines have most likely been run on non-detergent oil. If you are running an early unrestored engine that is not spotlessly clean internally, it is imperative to continue to run it on non-detergent oil. Otherwise there is the risk of damage to the engine. Non-detergent oil was used before oil filters became standard equipment. This type of oil would "stick" contaminants to the sidewalls and valleys of the engine to prevent dirty oil from damaging bearing surfaces.

Engines that have been run on non-detergent oil for many years will have a thick "sludge" buildup. Sludge will appear to be oil that has turned to gelatin except that it will be very black with contaminants. Using detergent oil in an engine that had been running non-detergent oil would allow these contaminants to be released to flow through the engine. This could result in serious damage to the rod, main and cam bearings as well as other engine components such as lifters and plugging of oil lines. After an engine has been rebuilt or thoroughly cleaned, use straight grade 30 WT or multi-grade 10-30 or 10-40 WT detergent oil to keep the engine clean. Early oil filters only filtered a small portion of the oil flowing through the engine. Unlike modern, full flow filters, these add-on filters are more of a decoration than real protection for the engine. Even if your engine does not have an oil filter, the number of miles a vintage car is driven is much less than when these cars were new. The simple solution is to change your oil more often. Every 500 miles or a minimum of once per year is a good rule of thumb.

[shooter]

Larry , back in the early sixties when my Dad was rebuilding a lot of engines I can remember when he pulled the valve covers off sometimes there would be a "sludge" valve cover underneath.