Can I Use 75w90 Instead of 75w140?: You Should Know
When my customer asks, “Can I use 75w90 instead of 75w140?” I replied positively; then, I wanted to know their vehicle engine capacity and load. Mainly 75w90 & 75w140 are synthetic gear oil that can be used for high-load capacity trucks or oversized vehicles. They keep the safety of your engine parts and don’t allow any friction between metals.
However, these two gear oils have some fundamental differences you can consider while selecting the best one. They both are suitable for the winter season and can protect your engine from loaded damage and other frictions. Let’s get some ideas about these two oils and then get your query.
Overview of 75w90 Oil
The 75w90 is mainly a gear oil that is mainly used for mailboxes. You can also use this gear oil in your heavy truck that can bear a good amount of load and give you the best support. Primarily, it works better in winter when your engine struggles to get started and maintain that weight. Going through the oil, you will find different meanings for every part.
Here, W refers to the winter season, which indicates that this oil is mainly for the winter region. It has a thicker viscosity level that helps the heavy-loaded truck or train to maintain its metal parts from extra frictions. That’s all about 75w90 gear oil.

Overview of 75w140
It’s also similar to gear oil that people mostly use on heavy trucks. It can bear the highest load and support your engine best in winter. You can expect to run your heavy-loaded truck smoothly in winter: it will not let your engine get stuck or stop suddenly. All engine parts will get equal quality lubrication to avoid friction, become healthy, and keep fit for a long time.
Can I Use 75w90 Instead of 75w140?
Yes. You can use 75w90 instead of 75w140. It is cheaper than the second gear oil and can give you 100% protection like the 75w140. Mainly, the difference between these two oils is viscosity level. 140 refers to a higher viscosity level than 90.
It’s an easy math equation that you can understand soon. Most of my customers are unwilling to spend extra bucks on getting 75w140 gear oil since they can save up to $50 every time. Will you pay more to get similar oil? I believe you won’t do that though some viscosity changes between these two oils.
Moreover, the 75w90 can be used for 75w140 gear oil. It will not damage your high-power engine that much. If you have any concerns regarding your engine horse-power & gear oil, I’d suggest going for 75w140 to get quality support for your overloaded truck or cargo ship. However, the 75w90 can also manage the high viscosity and high load. If you ask a professional about their core differences, he will notify you about the viscosity.
Apart from that, the 75w90 will contain all the characteristics of 75w140 gear oil. When you require the second oil for higher viscosity, I don’t mind suggesting you use this gear oil for optimized and safe operation.

Is 75w90 the same as 75w140?
No, they are not precisely the same since they have some identical characteristics. The first one has low viscosity, and the second one has high density. So, the second one can handle the loaded truck better than the first one. Besides, the first one is cheaper than the second one.
Is it safe to use 75w90 instead of 75w140?
It’s safe to use 75w90 instead of 75w140 since they don’t have that much dissimilarity and issues in altering them. Your vehicle engine gear will love to have both of them with a little difference in viscosity level. When you have issues regarding viscosity, you cannot use one instead of the other.
Can I Mix 75W90 with 75W140?
Yes, you can mix 75w90 with 75w140 since they will mix and become a balance gear oil. Considering the new viscosity level, you will find an incredible number there. They will indeed mix together and give you a perfect solution for your loaded engine.
Closing Words
Can I use 75w90 instead of 75w140? Yes, you can. But the problem is your engine requirements. Suppose your engine asks for the 75w140 for that specific viscosity level. In that case, you should not use the 75w90 here because they have a little difference in viscosity that might affect your engine productivity.