It really seems like straight grade SAE 20 for winter and SAE 30 for summer, is the way to go with the 235.
I got mine 10 years ago and drove it every day since, maybe 85K miles. Rebuilt the head last year, but don't know when the block was rebuilt last time.
Used 10W-40 in the winter and 20W-50 in the summer for the last 5 years.
Then I read about multi-grade oils and how they work. Can't say I was thrilled about the polymers and that they start breaking down after just 1500 miles.
So last week I replaced the 20W-50 oil with SAE 30 and sure enough a 250 mile freeway drive through the hot desert at 2500-3000 rpm showed clear results:
With the SAE 30 the oil pressure dropped a little, but the engine stayed cooler than with 20W-50.
It's really true what many said all along - don't worry too much about making the oil thicker and raising the pressure on the gauge.
That doesn't necessarily mean that the engine gets better lubrication.
Pure oil in the right grade for the season is the way to go.
Now, I am still adding Lucas additive, because the block hasn't been rebuilt in probably 100K miles.
When I rebuilt the head, I was astounded how good the condition of the pistons are.
No gasket leaks, no blow by, nice compression around 120. Man, I love these engines.
Is there anybody out there who advises against using Lucas Additive?
Anyone I talk to always recommends it as the only additive that works.
But I wonder what's the other side of the coin?
Any down sides...?
