good SL dino oil? 96 XJ

I know this topic has been run through over and over, and i've read the threads but it's all a bit overwhelming.
To my understanding, our flat tappets need an SL oil right? higher ZDDP levels right?
Soooo...too broke to fix the mainseals (slight seep) so I'm sticking to dino a few more times.
Can someone recommend a good conventional oil that has the right levels of ZDDP.
last change I switched from Valvoline high mileage 10w-30(dino) to valvoline max life syn blend 10w-40 and got a little less seepage, but it seems to have lost a little power.
I stand at a crossroads awaiting direction:eeks1:
thanks all!
140000 on the clock

I prefer super tech - can be found at yer local wal mart - all the oil has to pass tests before it goes to market so i'm not about to pay for name brand - NOW, in the case of super high performance synthetics like royal purple, amsoil and such theres alot of different additives and things that make them better but regular oil ... nah

I like rotella 15-40

I just put in Mobil 5000 10wt-30 cheepo from Walmart. It meets SL requirements.

Re: good SL 'blend' oil? 96 XJ

Well it looks like almost all oils meet the older requirements. I also realized I've been running syn blend for a whle now. Guess I'll stay with a blend then. Thing is, on the Valv High mile 10-30 in the API seal :
"API service SM, SAE 10w-30". I don't see SL in the seal:eyes: WHy is that?
On the SIDE it says: "API services SM/SL ACEA A-1 protection and all preceding API gasoline categories. Meets or exceeds all Protection requirements of ILSAC GF-4" whatever that means.
The question posed is "which syn blend has the most ZDDP and additive package (old seals) for my I6?"
On a side not what strted this search was the loss of power going from 10-30 to 40. I figure if zinc is what helps keep/restore power maybe I could get more and have longer engine life and power.

I'm down to these two choices: Either castrol synthetic blend for high mileage 10-40 or Valvoline Max life 10-40.
The Castrol is Base oil refined95% and Zinc Alkyl dithiophosphate 0-5% (ZDDP?)
The valvoline is Petroleum distillates and hydrotreated heavy paraf 90%

Both are SL compatible, one has the good stuff in it but is base oil.
One has no base or good stuff but I've been running it a year now no prob.
Of these 2 choices which would you choose?
Really appreciate the help, wish I could go full synthetic. Just can't afford to fix the leaks yet.

For a blend I would go with either Castrol Syn-tec blend or valvoline's blend. For full syn, I would say Amsoil hands down, otherwise.. Valvoline Synpower is great, it is one of the few that has zinc in it