OK, read up on the citrus flush and only have one question. I realize that the proper procedure is drain, fresh flush, soap (de-oil) flush, fresh, citrus flush (2.2 lbs), the really good flush, add approx anti freeze, approx 50%.

The question is "will it hurt to leave the citrus flush in overnight?" Most of my mileage is at night, so, I want to get up to adding the citrus flush, then go on my nightly commute, which is probably one hour each way. Then the next morning, warm up the car, then continue with the rest of the procedure. BTW, the nights are staying in the low 80s...

Any real problems with doing it that way? Comments?

Car is the 87 SDL listed below

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87 300SDL - 215K Miles !!
99 F-350CC Dually PSD - 190K
86 300SDL - 189K
All on B-100

I'd worry about the acid eating away more than it was intended, especially with the aluminum head.

Personally, I don't think that concentration of citric acid could hurt much of anything overnight, but, I've never tried it.

Also, after you drain the citric acid solution, you really need to fill and drain about three times to get every last bit of the solution out of the engine. Using the block drain is strongly encouraged. Driving the vehicle between fills is strongly encouraged.

It's a time consuming and lengthy procedure to do properly.