this is all I can find but it's more for clothing than a car seat
Introduction
Whether it's a cooking, automotive or lubricating oil mark, the sooner you deal with a greasy stain, the better the outcome.
Instructions
Difficulty: Moderately Easy
Steps
1Step OneApply an absorbent such as talcum powder or cornstarch to the affected area, then brush away. If the stain is heavy or old, proceed to Step 2; if fresh, skip to Step 3.
2Step TwoPlace stain facedown on paper towels. Blot back of stain with a dry-cleaning solvent. Replace paper towels as they soak up the stain.
3Step ThreeSpray with laundry pretreatment.
4Step FourWash in the hottest water that's safe for the garment.
5Step FiveAir dry.