Ok, there may not be much new info in this post for many, however I thought I'd share my process for cleaning the steering wheel stitching and subsequently the steering wheel leather. This is the first time I've done a complete clean on this vehicle's steering wheel, though I have applied Leatherique Pristine Clean a few times since 2017. I spent maybe 30m preparing and getting to the wrapped steering wheel part. Then another 30m after the 24hour wait period...but I'm fairly slow.
Apologies, I failed to take BEFORE pictures. You'll have to trust me that there was a tangible improvement. However it looks, note this won't perform miracles, so temper expectations.
DISCLAIMER: This method worked well with my OEM leather Steering Wheel for X5M. It may not work the same for everyone. Prior to proceeding, test process on backside of steering wheel to confirm chemicals pose no threat to your steering wheel leather and stitching. I also tested this process on a 1998 OEM E36 M3 steering wheel (that's leftover from my E36M3 sale a while back - btw night/day improvement) with no issues. Also used on a 2016 Honda Pilot Elite steering wheel with no issues.
STITCHING
-IMO this should be done first, then clean the leather with Leatherique Rejuvinator. Lots of options out there, but I keep coming back to this product for deep cleansing and conditioning.
-Use microfiber pad to dab Oxyclean onto M Stitching. Then gently rub Oxyclean into M Stitching in circular motion with pad.
-Use Chemical Guys Nonsense Invisible Super Cleaner and microfiber towel as if gently wiping off Oxyclean from steering wheel. It may produce a fine lather.
-Use microfiber towel with warm water to 'rinse' off chemicals from steering wheel leather and m-stitching.
-Use microfiber towel to gently remove dampness from leather and stitching. Allow to air dry.
-Repeat if necessary for extra soiled threading. I recommend repeating process
instead of leaving Oxyclean on stitching and leather to soak for some amount of time. No need to soak stitching IMO.
-NOTE: I don't recommend anything other than gentle action on these materials. A heavy hand can cause damage.
LEATHER
-There are many leather products but I've been using Leatherique since 2003. It's quite a tedious processes, especially if you have large surfaces to treat, but the results have always been worth it. For the full process expect hours or if you have the time, days. The finish is matte (almost like brand new) and not glossy or wet looking (see pix below). There is relatively no odor and I use it once a year, maybe twice. Whatever you do
DO NOT SCRUB or USE FORCE to apply leatherique (or any product) into your leather unless you want to remove the dye. I saw one post where someone used a scrub brush and were disappointed to see the dye disappear. I recommend only using your hands or gloved hands.
-FWIW I do like the smell of leather and between Leatherique applications I use Zaino Z9 (cleaner) and/or Z10 (conditioner). I've tried many products that claim new car leather smell, but these Zaino products are my favorite leather smell. Surprisingly, even the drive-thru folks comment about the pleasant leather smell…or it's a hint I used too much?? It last a couple months, then reapply. The Z10 is apply and allow to dry, EASY. I admit, I'm unsure if they do any cleaning or conditioning, but the smell left in the car is why I use.
-Using rubber glove, apply generous amount of Leatherique Rejuvinator leather cleaner. Gently, without use of force, roll gloved hand with Rejuvinator over surface multiple times.
-DO NOT apply Leatherique to stitching. Note, I've applied Leatherique to stitching many times before w/o any noticeable issues. However, after just cleaning stitching I didn't want to risk discoloring the stitching given the Rejuvinator is brown.
-Wrap steering wheel with Suran Wrap and allow to sit for as long as you are able…preferably with a warm interior environment, out of direct sunlight (IE: leave outside but put up your sunshade). I left mine on for about 24 hours in the garage (low 80's F temp).
-Using a rubber glove, apply a generous amount (not dripping off steering wheel) of Leatherique Pristine Clean leather cleaner to remove Rejuvinator product.
-In the few minutes while that soaks, grab your microfiber towel, take to the sink, soak in warm water, and wring. Return and GENTLY wipe down the steering wheel where you applied product. I used a bright yellow microfiber towel and you can see the dirt removed and what remained after a simple no soap rinse with hot water. I suppose some of what remains could be dye, but very, very little. I couldn't capture in the images, but the rinsed towel actually looks much cleaner than pictured, not sure why. The takeaway is don't do any scrubbing.
-Using a dry microfiber towel, gently polish away damp areas. Allow to air dry.
-Some time later, return with a flashlight and examine the steering wheel closely…you're bound to have missed some spots. If so, wipe down gently with wet microfiber towel and polish dry.
Not bad for an 8.5 year old steering wheel!