My dad won't listen to me when it comes to my son.

Backstory; My Chinese dad is a great guy who did a lot for me. A lot. He worked hard, gave up every little free time he had to take me out to places and fed me. Hower, he rarely said no to me. I was a super spoiled kid who knew absolutely nothing about boundaries. I wanted to have an N64 and PS1? I got them both. I wanted to eat a 3rd icecream cone? I got it despite my mother saying no. I wanted money to go shopping with friends? He'd give me extra after my mom gave me 20 dollars. All in all, he was the complete opposite you'd hear about traditional Asian parents.Even now, as an adult and having learned about boundaries, rules and all that you need to be a good functioning person, I can't say I dislike my dad. I love him, dearly, but the behaviour he's shown towards me as a child, he's doing to my son now and I can't talk him out of it.My wife and I both work full-time and our son (OS) goes to school only for half-days (long story short; he still goes to pre-school and teacher thought it'd be a good idea to only let him come for half a day until kindergarten starts so he can get adjusted to school-life).So our solution was to ask my parents for help. My mom, who was the strict one back then and I'm really grateful to her, was delighted and so was my dad. We bring him to school, they pick him up and watch him until we pick him up from their place.At first we didn't notice any change, but about 2-3 months in we noticed how OS got really fussy about things. This wasn't the typical stubborn toddler things, but he'd get angry a lot faster than we're used to and would throw tantrums (like for example, throwing himself on the floor at all times until he got what he wanted). It wasn't the first time he threw a tantrum like that, so we just waited the tantrums out. Once he knew we wouldn't give in he'd slowly calm down and we'd talk to him. However this time? He was crying and shouting for an entire hour, just laying there and flaying about. I got so annoyed by it that I had to leave the room to shout in a pillow while my wife stood there watching OS.It wasn't until my wife suggested it might've been my dad who was spoiling him. I asked my dad and he admitted to being really lax when it came to boundaries and rules. "Come on, he's a kid!" he said. So I asked my mom what had happened and she explained that behind her back my dad would just let him play games on his phone, sneak him cookies and snacks, let him watch cartoons all day long if my mom had somewhere to be, giving things to him when he'd start throwing a tantrum about it, etc. A good example; In our house, he can't play with the pots and pans because they're heavy and he might drop one on his foot. He can help me cook, he can help me do kitchenwork, but he's not allowed to touch the pots and pans for that reason alone. He knows this. At my parents? He reaches for a pot, starts laughing, I tell him to not touch it and to push it back, my dad interjects telling me it's fine, the pot falls from the kitchen closet, a few inches away from his toes. I get angry and tell my dad to back off, he tells me I'm being too strict.The worst thing is that when we're being strict with him when my dad is around, he'll pull OS closer to him and start laughing and saying "Oh it's ok it's ok, haha!" or something 'comforting'.I went to talk to my dad about this and he said that I was raised the same way, and that I turned out fine so I shouldn't worry too much. "Besides, he's only a toddler, you can be strict with him all you want when he goes to highschool, but you need to spoil him now or he will dislike you for being too strict!" At times he'll say "ok ok, you're the parent," because I'm sure my mom will have complained to him.​So now I don't know what to do. I feel like I'm talking to a wall. OS is half a day there (except for weekends) and we noticed that over the course of a few months his behaviour has been getting worse and worse. He doesn't understand (yet) that our home is our rules, and that his grandparents' house is their rules.​Importantly, I should note that my dad isn't a terrible grandparent. I know it seems like I'm making him out to be like this, but he will take OS out to play at the playground, he will follow some of the rules we have set up, etc. When I offered him up the idea of babysitting OS for 5 half-days a week, he didn't skip a heartbeat and said yes immediately. He's a good dad, but very stubborn. It's just killing us to get OS back who won't listen to 50% of what we're asking him to do anymore.​Has anyone experienced anything similar? Am I just overreacting and will this eventually blow over? Does anyone have any tips? via /r/Parenting https://ift.tt/2XaDCKH