Hi John, nice heavy weathering and looking good. Here's a tip if you'd like to try and also if you haven't added a top coat to the weathering as yet. Now that the initial wash has a bite or is semi cured, you could use either of these, cotton bud, broad flat brush or soft cloth. Soak them in turps or thinner and do a wipe from front to back to create streaks with the wash. In this way you can also control the amount of wash. Same can be done for oil or fuel stains by dabbing spots of oil paint and streaking with a brush loaded with thinners.
Cheers,
Richard