So oil fill cap says to use 5W30, I have a lot of stash of 0W20, 5W20 and Can I use either of them?

It'll be a DD, no track or anything aggressive in terms of driving.

I'll stick to synthetic for now, should I do it or no?

Any link to a UOA report would be much appreciated, thanks again.

Well, usually as engines age, it's recommended to move UP in viscosity as well as starting to use High Mileage spec. You're wanting to go backwards.... hmmmmm.

Buy a jug of 10w40 and blend 50/50 for a 5w30 viscosity. Should be cheap to do.

I'd just go to Walmart and grab a jug of synthetic 5W30.

Best advice so far

I'd do what Artem suggests and just get some thicker oil to blend and target a 30 weight. Maybe an xW-50 to be able to use a higher ratio of the 20 weight. I don't believe that generation of TSX was back spec'd to anything lighter than a 30.

I'll stick to 5W30 Mobil1 then

BTW, curious if I can blend M1 0W40 and 0W20 or 5W20? 50/50

Using this calculator: http://www.widman.biz/English/Calculators/Mixtures.html

And the data from here:
https://www.mobil.com/english-au/passenger-vehicle-lube/pds/glxxmobil-1-0w40
https://www.mobil.com/english-us/passenger-vehicle-lube/pds/glxxmobil-1-0w20

Mixing them 50-50 would result in a viscosity of 10.79 cSt (@100C), which would put it squarely in the 30 weight range.

http://www.viscopedia.com/viscosity-tables/substances/sae-viscosity-grades/

Even a 20% mix of the 0W40 and 80% 0W20 would result in a 30 weight.

Edit: and yes, you can definitely mix them!

Thanks so much EdwardC. I actually found Penzzoil Platinum 5W30 in my stash, so planning to use from it!!!

Always good to know I can mix 0W40 and 0W20, to get close to 30wt.

BTW, can Euro 5W30 be used too? Made for TDI, Diesel engines?

Thanks again.

Here's what I wrote about mine 3 months and 6k miles ago:
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4522636/06_TSX_-_Under_VC_-_223k

Great looking photos -- hoping when I open mine up soon for the timing belt/water pump service & valves check/adjustment it looks 1/2 as clean as yours.

So you have a big stash, run your quality 5W30 Synthetic on par with the MM & you will be fine. Mixing oils in the same brand name is no big deal & have done it many of times over the years to come up with some kinda blend number.

Dude, the K24 engine in your TSX has a timing chain... you'd only need to pop the valve cover to adjust valves and maybe replace a leaking valve cover gasket. Unless you've got some major chain slack / slap going on, it should be good for the life of the car.

Guessing he's talking about the TL in his sig, which has a belt.

Cpayne5, I appreciate your advice and confidence inspiring feedback for TSX, because of which I pulled the trigger

I am looking forward to see if it burns any oil or no? Also, PO has used 'regular' gas in it for almost 110K(which he has put on), I filled full tank yesterday for ~$45 with Prem though.

Any other advice you would give? Planning to do all fluids change once it gets a bit better in terms of weather, it has been brutally cold!