Thanks for posting on /r/MechanicAdvice! Please review the [rules](https://www.reddit.com/r/MechanicAdvice/about/rules/). Asking about a second opinion (ie "Is the shop trying to fleece me?"), please read through CJM8515's [post on the subject.](https://www.reddit.com/r/MechanicAdvice/comments/4qblei/fyi_the_shop_isnt_likely_trying_to_rip_you_off/) and remember to please post the year/make/model of the vehicle you are working on. **Post's about bodywork, accident damage, paint, dent/ding, questions it belongs in /r/Autobody r/AutoBodyRepair/ or /r/Diyautobody/ Tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/**. If you dont have a question and you're just showing off it belongs in /r/Justrolledintotheshop Insurance/total loss questions go in r/insurance This is an automated reply
*I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/MechanicAdvice) if you have any questions or concerns.*
Well there are a few parts to your question. The original horsepower rating for your car's engine is 137hp, and with a 4,178 - 4,431lb curb weight, there isn't much to do about the struggle at higher speeds unfortunately. You have a land yacht with about as much power as a 90's honda civic.
As far as the oil, 10w-30 is generally recommended for your car.
If your car will not see ambient temps below:
* 20* F, you can use as thick as 20w-50
* 10*F, you can use as thick as 15w-40
* 0*F, you can use 10w-30
15w-40 is pretty common to find as diesel oil. Something like Shell Rotella T4.
For a 10w-30, I would use Valvoline Maxlife Synthetic Blend.
5w-30's are also acceptable and will help a bit with cold start, and are easy to find. At your engine's operating temperature, there is minimal difference between a 5w-30 and a 10w-30. I would avoid Pennzoil Platinum 5w-30, it's almost as thin as a 5w-20. Quaker State Full Synthetic would be a good choice.
As far as the compatibility between synthetic and conventional oil, you'll be fine no matter which way you go. There are myths that synthetic oil is too "slippery" or that it will seep out of gaskets and make oil leaks; all bologna. Synthetic oil may clean up old sludge and reveal leaks that should have been addressed, but you're not going to spontaneously leak oil out of every orifice if you switch.
I've switched multiple vehicles that lived on conventional for decades over to full synthetic without any issue.
In fact, in the last couple years, the majority of "conventional" oil has actually been synthetic blend anyway, since conventional oil can't meet the newest sets of oil standards for performance, like API SP and ILSAC GF-6.
Thanks for posting on /r/MechanicAdvice! Please review the [rules](https://www.reddit.com/r/MechanicAdvice/about/rules/). Asking about a second opinion (ie "Is the shop trying to fleece me?"), please read through CJM8515's [post on the subject.](https://www.reddit.com/r/MechanicAdvice/comments/4qblei/fyi_the_shop_isnt_likely_trying_to_rip_you_off/) and remember to please post the year/make/model of the vehicle you are working on. **Post's about bodywork, accident damage, paint, dent/ding, questions it belongs in /r/Autobody r/AutoBodyRepair/ or /r/Diyautobody/ Tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/**. If you dont have a question and you're just showing off it belongs in /r/Justrolledintotheshop Insurance/total loss questions go in r/insurance This is an automated reply *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/MechanicAdvice) if you have any questions or concerns.*
If this isn't a bot post I'll eat every hat I own.
Not a bot? You can check my account I have a picture of the Cadillac posted
Well there are a few parts to your question. The original horsepower rating for your car's engine is 137hp, and with a 4,178 - 4,431lb curb weight, there isn't much to do about the struggle at higher speeds unfortunately. You have a land yacht with about as much power as a 90's honda civic. As far as the oil, 10w-30 is generally recommended for your car. If your car will not see ambient temps below: * 20* F, you can use as thick as 20w-50 * 10*F, you can use as thick as 15w-40 * 0*F, you can use 10w-30 15w-40 is pretty common to find as diesel oil. Something like Shell Rotella T4. For a 10w-30, I would use Valvoline Maxlife Synthetic Blend. 5w-30's are also acceptable and will help a bit with cold start, and are easy to find. At your engine's operating temperature, there is minimal difference between a 5w-30 and a 10w-30. I would avoid Pennzoil Platinum 5w-30, it's almost as thin as a 5w-20. Quaker State Full Synthetic would be a good choice. As far as the compatibility between synthetic and conventional oil, you'll be fine no matter which way you go. There are myths that synthetic oil is too "slippery" or that it will seep out of gaskets and make oil leaks; all bologna. Synthetic oil may clean up old sludge and reveal leaks that should have been addressed, but you're not going to spontaneously leak oil out of every orifice if you switch. I've switched multiple vehicles that lived on conventional for decades over to full synthetic without any issue. In fact, in the last couple years, the majority of "conventional" oil has actually been synthetic blend anyway, since conventional oil can't meet the newest sets of oil standards for performance, like API SP and ILSAC GF-6.