Way too thin for a 27 year year old motor.
5 weight synthetic is already more fluid than conventional oil of the same weight.
Nonsense... I'm running synthetic 5W-30 in my 20 year old Acura right now. At operating temperature it should be just the same as a conventional 30-grade. You should try to get the lowest W (winter) rating possible if you're going to just be using it in the winter, as the warm-up period is when most of the wear occurs and more flow is better in that situation.
Even a 0W cold is still way thicker than it will be at operating temp...
Im worried about consumption and leakage !
If you're worried about that (and I don't blame you, those seals are probably pretty hard after 27 years), try a high mileage synthetic such as Mobil 1 HM, Royal Purple HMX, or Valvoline MaxLife full synthetic. Best of both worlds in your situation, IMO.
Napa Synthetic 5w30. On sale for $3.79/qt this month. It's rebranded Synpower.
Another good deal is PP 5w30. $22.66 at Walmart for 5qt, and there's a $10 rebate.
PP is cheaper after rebate, but it's the big 5-qt jug and you have to wait 3-4 weeks to get the rebate, and some people don't like WM.
The advantage to Napa syn is the single quart bottles, so when you just have a little bit left, it's just one quart left or half a quart in the same small bottle, rather than having a big jug left behind for just a quart or less. Plus, the single quart bottles are easier to pour from.
Either one will serve you well.
The M1 AFE 0w30 is also a good choice.
Ive been using Amosil OE 5w30 for the past 2 seasons and on initial cold startup, Ive noticed bottom end knocking, then goes away when warm.
My 04 ram had a bottom end knock when cold usin M1 afe 0w-20,on tigs advice. It wasn't noticeable when warm though.
I used defy 5w-20 on the next oil change and no knock.
Not that I thought the oil itself was a problem.
In fact winter starts were a breeze. -35 and it wasn't plugged in and started just fine.
As far as consumption goes unless the engine is badly worn there shouldn't be much difference between a 0w-30 and a 10w-30.
And if you are concerned about dried up seals use an oil with an ester in it like redline or use an additive with an eater in it like liqui-moly motor oil saver.
That motor oil saver will improve the pliability of and rubber or cork gasket,as long as it's not made of rope.