SAE 20wt is still available but if your local parts store won’t order you in a case then you can find it by the case from Amazon among others. When i was working for a parts store we back in the mid 90’s we didn’t get a huge demand for the 20wt but kept it on the shelf, but with the way most chain stores work if the demand is weak then something else that sells better will take it’s place. http://www.amazon.com/gp/product/B0052KY07C/ref=s9_simh_gw_p86_d0_i3?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=06RBCEPPARZ2WQWWCWP8&pf_rd_t=101&pf_rd_p=1688200382&pf_rd_i=507846
I fear folks will be buying that to use in their engines that require detergent oil. Non-detergent was way back for flat head engines, air compressors, machinery, etc.
Thanks for the replies. I dont think the caddy had an oil light of any kind. But then again, non of the lights work in the dash except the occasional turn signal indicator and high beam indicator!
I should mention the engine has a good bit of sludge in the pan, which I plan to drop one day and clean. Maybe the detergent oils will help some. Who knows. Right now ill leave the 10w30 in, along with the STP additive that contains zinc.
I checked the trans fluid yesterday and it was clean, although a little high. Might have to drain some.
The STP additive, is this the thick stuff that looks like clear honey? I’m not sure traditional STP has any zinc in it…It claims to be “100%” petroleum…
A sludge inspection can be performed by removing a valve cover and inspecting the rockers…A 10 minute job…
It says on the front of the bottle contains ZDDP.
I know it has sludge because I have to poke through it after removing the drain plug! Haha
Yes, STP has jumped on the ZDDP bandwagon. I’d rather add something just for the ZDDP, I don’t like all the other stuff in STP.
" I’ve heard 10w-30, 10w-40, 20w-50, 15w-40."
All those oils are so far ahead of 1950 oil I bet they’d all do the job fine.
I’d just use 15W-40 diesel rated and call it a day.
Apparently zinc is to avoid engine damage at startup.Woopty woo.Diesel oils are better and made to carry deposits better for a cleaner engine.Rotella is a fine oil w/a good reputation.However, since your engine is broken in, and high mileage I don’t see a problem using the “high Mileage” oils available today.Any oil today is better than that of the past, they’ve learned alot over the years.I believe most of the high mileage oils are prtial synthetics.I recommend 15W-40 Mobil 1 Full synthetic,but if you have leaks synthetic will find them and drip more than regular oil. Or Valvoline “Max Life” and use whatever weight you see fit.