conditioner only washing won't shift that, why would you want to put petroleum jelly on your scalp? It won't penetrate, you will get much the same occlusive (barrier/ sealant) benefits from any natural oil or butter and many will shift with conditioner only washing.
If I was to treat my scalp with an oil or butter I'd use something lower in oleic acid (irritant) and higher in stearic and/ or palmitic acids and/ or cholesterol (all strengthen the skin barrier). Unrefined west African shea and lanolin are lovely for skin health, thick tho so would dilute them down/ soften with a lighter oil, perhaps borage for the GLA or whip up some shea-aloe butter. Egg lecithin aids production of ceramides which strengthen skin and hair.
2a-2c, medium texture, porous/ colour treated. Three years CG, growing out mechanical and chemical damage = breakage and very high porosity. Past armpit length heading for waist.
Treatments: Komaza protein, Komaza Matani, coconut oil with sugar syrup. Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss ultimate volume
Styler: Umberto Giannini jelly, Boots curl creme, Rockin RInglets
Experimenting with: Mega-Tek, Curl Harmony reviver, Elvive Full Restore 5.